History

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Consumer Confidence Report

2026

For the year 2025

City of Corona

Utilities Department

“Protecting Public Health”

Message from the Director of Utilities

We are pleased to present this year’s Consumer Confidence Report. In this report, you will find vital information about the quality of your drinking water and the standards we follow, as set by the United States Environmental Protection Agency (USEPA) and the State Water Resources Control Board (SWRCB).

At the Utilities Department (UD), ensuring the safety and reliability of your water is our highest priority. Our highly trained Water Operations staff conduct daily sampling. These samples are then sent to independent and certified laboratories for thorough testing. In 2025, we conducted 5,150 water quality tests to monitor water quality and deliver the best possible blend of water directly to your tap.

This report summarizes data from the water produced and distributed throughout 2025. It includes information regarding where your water comes from, how it is treated, and how it compares to regulatory standards. I’m proud to share that our water met or exceeded all USEPA and State health standards throughout the year. Our dedicated team ensured that no primary Maximum Contaminant Levels (MCLs) were exceeded.

Thank you for trusting us to provide safe, high-quality drinking water every day.

Tom Moody

Director of Utilities

(951)736-2477

www.CoronaCA.gov

Corona’s Water Sources

In 2025, Corona residents and businesses used approximately 9.8 billion gallons of drinking water. Corona’s water supply comes from different sources: groundwater wells owned and operated by the City of Corona provided 45.5%, 49.6% came through Lake Mathews from the Colorado River, and 4.9% was from the State Water Project’s California Aqueduct.

Water Treatment Processes

The surface water from the Colorado River requires treatment to become drinking water. The treatment process is accomplished in the City of Corona’s two surface water treatment facilities: Sierra Del Oro and Lester. These facilities incorporate the use of coagulants, which bind small particles together to form larger particles that can be easily removed through multimedia filtration. After filtration, the water is treated with sodium hypochlorite to kill or inactivate harmful organisms. This part of the processis called disinfection.

Through independent laboratory testing, 100% of the samples taken in 2025 were free of harmful organisms.

Most of the groundwater pumped in Corona was sent through a state-of-the-art reverse osmosis membrane treatment facility, the Temescal Desalter. This facility provides removal of nitrates, per-fluorinated compounds, 1,2,3-Trichloropropane (1,2,3-TCP), perchlorates, and suspended and dissolved solids. The UD adds an ammonium hydroxide solution to the disinfected water, which in conjunction with sodium hypochlorite forms a compound called chloramines. This chemical acts as a disinfectant in the distribution system and remains active for a longer period of time than sodium hypochlorite alone. It also helps reduce the formation of disinfection byproducts that could be harmful to our health. Disinfection byproducts are formed when some disinfectants like chlorine react with naturally occurring organic matter in the water.

Blending

The UD has five blending facilities that blend treated groundwater sources with raw groundwater sources and treated surface water to deliver safe, reliable drinking water to your tap. You will notice in the tables of detected contaminants that the groundwater exceeded the primary standard for arsenic, nitrate, perchlorate, selenium and 1,2,3-TCP.  The UD is required by law to report the range of all raw groundwater samples monitored, as well as the average concentration delivered to your tap. The averages of what you receive at your tap are much lower because the UD treats and blends water from several sources to improve water quality. The blending stations are continuously monitored and routinely sampled to ensure that the water delivered to your tap meets all health standards with a safety margin of no less than 10%. Please refer to the “Treated Average System Water” column in the tables at the end of the report for a more accurate representation of system water quality.

For more information about fluoridation, oral health, and current issues visit: https://www.waterboards.ca.gov/drinking_water/certlic/drinkingwater/Fluoridation.html.

Reclaimed Water

To improve water supply reliability for the City, the UD developed and began building our reclaimed water system in 2006. Utilizing reclaimed water to help meet water demands for the City reduces the impact of imported water supply shortages and costs. The reclaimed water system uses highly treated wastewater from our sewer treatment facilities and distributes it throughout the City. The reclaimed water system is separate from the drinking water system. Reclaimed water pipes, sprinkler caps, and signage are painted purple to easily identify them as part of the reclaimed water system. Reclaimed water is used primarily on landscaping at parks, schools, parkway areas, and a few commercial buildings. By re-using water we save potable water for our homes and businesses. A rebate incentive is offered for businesses that convert their landscape irrigation and/or process operation water use to reclaimed water. Save water and get funding assistance to cover the conversion. Contact the Water Resources Team at (951) 736-2234 or by e-mail at WaterRebates@CoronaCA.gov to see if your business is eligible.

The City of Corona’s reclaimed water system infrastructure consists of approximately 62 miles of pipeline, three storage tanks, and six pump stations.

Of the reclaimed water produced, 1.28 billion gallons went into the reclaimed water distribution system for customer use. We currently have 436 connections and are continually adding new sites.

Water Conservation

Our changing climate requires Californians to move beyond temporary emergency drought measures and adopt permanent changes to use water more wisely and prepare for more frequent and persistent periods of limited water supply. Conservation and efficiency also reduce the energy needed to pump, transport, treat and deliver water. Your small changes make a big impact. We ask that everyone be efficient in their water usage, by requiring all residents and businesses in the UD’s service area to follow the water use guidelines on the next page.

Water Use Guidelines

• No watering between 10 a.m. and 8 p.m.

• Odd-numbered addresses can water on Saturday, Monday, and Wednesday only.

• Even-numbered addresses can water on Sunday, Tuesday, and Thursday only.

• Watering on Fridays is prohibited. Since government institutions are not open on weekends, they may water three days per week of the agency’s choosing.

• Limit sprinkler station run times to help conserve water.

• Leaks and broken sprinklers must be fixed in a timely manner.

• Watering during and within 48 hours after rainfall measuring ½” or more is prohibited.

• Drip irrigation, which waters in gallons per hour, can water for a maximum of 90 minutes per day, provided there is no runoff.

• Water cannot be allowed to run off the property.

• All swimming pools, spas, ponds, and fountains shall be equipped withre-circulating pumps.

• Washing hard surfaces is prohibited.

• Vehicles can only be washed using a bucket and a hose with an automatic shut-off nozzle.

• In Corona, food establishments are prohibited from providing drinking water to patrons unless requested.

• Street trees must be kept alive.

Rebates for Water Saving Appliances and Devices

Improve the water use efficiency at your home by upgrading your appliances and fixtures to water efficient models. The UD offers rebates for the following water saving appliances, devices, and fixtures:

• High Efficiency Clothes Washer

• Premium High Efficiency Toilets

• Weather Based Irrigation Controllers

• Soil Moisture Sensors

• Rotating Nozzles

• Rain Barrels

• Turf Replacement

The UD also offers other residential rebates for a pool cover and a recirculating hot water device. For more information on these and other water efficiency rebates available to Corona residents, please contact the Water Resources Team at (951) 736-2234 or e-mail WaterRebates@CoronaCA.gov.

Water Efficiency Rebates for Businesses

The UD offers numerous rebates just for businesses to help them improve water efficiency. Available rebates for devices and fixtures include:

• Premium High Efficiency Toilets

• Ultra-Low and Zero Water Urinals

• Plumbing Flow Control Valves

• Air Cooled Ice Machines

• Connectionless Food Steamers

• Dry Vacuum Pump

• Laminar Flow Pumps

• Conductivity and pH Controllers for Cooling Towers

• Weather-Based Irrigation Controllers (WBICs)

• Soil Moisture Sensor Systems

• Rotating Nozzles for Pop-Up Spray Heads

• Large Rotary Nozzles

• In-Stem Flow Regulators

• Turf Replacement

• Reclaimed Water Conversion Program (where available)

For more information on these and other water efficiency rebates available to Corona businesses, contact the Water Resources Team at (951) 736-2234 or e-mail WaterRebates@CoronaCA.gov.

Corona Recycles

What is California Senate Bill 1383 (SB 1383)?

Senate Bill 1383 (SB 1383) is California’s organic waste recycling legislation. Effective January 1, 2022, all Californians are required to source-separate organic waste from their trash and recycling. Organic waste includes yard waste, food scraps, and food-soiled paper.

Why SB 1383?

Diverting organic waste from our landfills helps to reduce greenhouse gas emissions that contribute to climate change.

• Every 2 ½ tons of food rescued is the equivalent of taking 2 million cars off the road for a year and aids in feeding 1 in 4 food insecure children that go hungry in California.

• Organic waste in landfills emits 20% of California’s methane, a super pollutant 84 times more potent than carbon dioxide.

• Disposing of organic waste properly helps limit air pollutants that contribute to health conditions.

Who Collects my Organic Waste?

Waste Management will collect your organics and transport it to a facility that converts it into nutrient rich compost. You may also compost the materials at home. Adding compost to your soil reduces watering needs, adds nutrients, and eliminates the need for chemical fertilizers.

Questions? Email us at CoronaRecycles@CoronaCA.gov, or visit our website at https://bit.ly/coronarecycles.

From Your Drain to the Environment – Keep It Clean

While water reclamation treatment removes most pollutants,even trace amounts of some substances may be harmful to the environment. The best solution is to prevent pollution from going down the drain in the first place.

Dispose of unwanted medicine properly… No Drugs Down the Drain!

For years, unwanted medicine was flushed down the drain to protect children and pets from accessing it, and to ensure against illegal recovery of controlled substances. Today, there are better options. Please visit the U.S. Food and Drug Administration website for more information on how to dispose of unused medicine: https://www.fda.gov/forconsumers/.

Keep drains free of FOG – Fats, Oils, and Grease

When washed down the drain, cooking fats, oils, and grease, aka “FOG,” harden and block sewer lines. This causes raw sewage to backup into your home or onto neighborhood streets and storm drains, which drain to rivers and the ocean. Overflows can be costly and pose health and environmental hazards. Keep your sewer lines FOG free by allowing it to cool then scraping cooking fats into the garbage or into a container, such as an old metal coffee can or food scrap recycling bin – never down the drain!

Sanitary wipes are another item that often causes blockages in the City’s sewer lines. They should be kept away from drains and should not be flushed down the toilet, even if they are labeled as “flushable”.

General Water Quality Information

Drinking water sources (both tap and bottled water) include rivers, lakes, streams, ponds, reservoirs, springs, and wells. As water travels over the surface of the land or through the ground, it dissolves naturally-occurring minerals and, in some cases, radioactive material, and can pick up substances resulting from the presence of animals or from
human activity.

Contaminants that may be present in source water include:

• Microbial contaminants, such as viruses and bacteria that may come from sewage treatment plants, septic systems, agricultural livestock operations, and wildlife.

• Inorganic contaminants, such as salts and metals, that can be naturally- occurring or result from urban stormwater runoff, industrial or domestic wastewater discharges, oil and gas production, mining or farming.

• Pesticides and herbicides that may come from a variety of sources such as agriculture, urban stormwater runoff, and residential uses.

• Organic chemical contaminants, including synthetic and volatile that are byproducts of industrial processes and petroleum production, and can also come from gas stations, urban stormwater runoff, agricultural application, and septic systems.

• Radioactive contaminants that can be naturally-occurring or be the result of oil and gas production and mining activities.

In order to ensure that tap water is safe to drink, the USEPA and the State Water Resources Control Board (SWRCB) prescribe regulations that limit the amount of certain contaminants in water provided by public water systems. U.S. Food and Drug Administration regulations and California law also establish limits for contaminants in bottled water that provide the same protection for public health.

Drinking water, including bottled water, may reasonably be expected to contain at least small amounts of some contaminants. The presence of contaminants does not necessarily indicate that water poses a health risk. More information about contaminants and potential health effects can be obtained by calling the U.S. EPA’s Safe Drinking Water Hotline (1-800 426-4791).

Some people may be more vulnerable to contaminants in drinking water than the general population. Immuno-compromised persons such as persons with cancer undergoing chemotherapy, persons who have undergone organ transplants, people with HIV/AIDS or other immune system disorders, some elderly, and infants can be particularly at risk. These people should seek advice from their health care providers about drinking water. USEPA/Centers for Disease Control (CDC) guidelines on appropriate means to lessen the risk of infection by Cryptosporidium and other microbial contaminants are available from the Safe Drinking WaterHotline (1-800-426-4791).

Nitrate

Nitrate in drinking water at levels above 10 mg/L is a health risk for infants of less than six months of age because it can interfere with the capacity of the infant’s blood to carry oxygen, resulting in a serious illness; symptoms include shortness of breath and blueness of the skin. Nitrate levels above 10 mg/L may also affect the ability of the blood to carry oxygen in other individuals, such as pregnant women and those with certain specific enzyme deficiencies. If you are caring for an infant, or you are pregnant, you should ask advice from your health care provider.

Arsenic

While your drinking water meets the federal and state standard for arsenic, it does contain low levels of arsenic. The arsenic standard balances the current understanding of arsenic’s possible health effects against the costs of removing arsenic from drinking water. The U.S. Environmental Protection Agency continues to research the health effects of low levels of arsenic, which is a mineral known to cause cancer in humans at high concentrations and is linked to other health effects such as skin damage and circulatory problems.

Source Water Assessment

In accordance with the Federal Safe Drinking Water Act (SDWA), the SWRCB Division of Drinking Water and Environmental Management developed a program, called the Drinking Water Source Assessment and Protection (DWSAP) Program, to assess the vulnerability of drinking water sources to contamination. Assessments of the drinking water sources for the City of Corona were completed in February 2012. The assessment concluded that the City of Corona’s sources are considered most vulnerable to the following activities not associated with any detected contaminants in the water supply: automobile – gas stations, chemical/petroleum pipelines, chemical/petroleum processing/storage, dry cleaners, historic gas stations, machine shops, metal plating/finishing/fabricating, mining sand/gravel, NPDES/WDR permitted discharges, plastics/synthetics producers, septic systems – low density [<1/acre], sewer collection systems, underground storage tanks – confirmed leaking tanks, utility stations – maintenance areas, and wastewater treatment plants. A copy of the completed assessments are available through the City of Corona’s City Clerk’s office at 400 S. Vicentia, Corona, CA 92882, or by using the online Public Records Request form at https://www.coronaca.gov/departments/city-clerk/public-records-request.

Lead and Copper Rule Monitoring

The Lead and Copper Rule (LCR) was developed to protect public health by minimizing lead and copper levels in drinking water. The LCR established an action level of 15 parts per billion (ppb) for lead and 1.3 parts per million (ppm) for copper based on the 90th percentile level of tap water samples collected. Lead and copper are sampled on a mandated three-year testing cycle with sampling conducted at the customer’s tap.

Parameter

Units

State MCL

PHG

State
 DLR

Date Sampled

90^th
 Percentile

No. Sites Sampled

No. Sites
 Exceeding AL

Lead

ppb

AL=15

0.2

5

2023

5

53

3

Copper

ppm

AL=1.3

0.3

0.05

2023

0.17

53

0

AL          Action Levels

DLR       Detection Limits for purposes
of Reporting

MCL       Maximum Contaminant Level

PHG       Public Health Goal

ppb        Parts per billion or micrograms per liter (μg/L)

ppm           Parts permillion or milligrams per liter (mg/L)

Lead

The City of Corona Utilities Department recently conducted a digital inventory of all water service lines, which is the pipe that connects your home, building, or other structure to the water main. The purpose of the inventory is to identify the material of these service lines and fittings, including the customer-owned side of the water service line. This inventory can be found at http://www.coronaca.gov/lead.

Lead can cause serious health effects in people of all ages, especially pregnant people, infants (both formula-fed and breastfed), and young children. Lead in drinking water is primarily from materials and parts used in service lines and in home plumbing. The Utilities Department is responsible for providing high quality drinking water and removing lead pipes but cannot control the variety of materials used in the plumbing in your home. Because lead levels may vary over time, lead exposure is possible even when your tap sampling results do not detect lead at one point in time. You can help protect yourself and your family by identifying and removing lead materials within your home plumbing and taking steps to reduce your family’s risk. Using a filter, certified by an American National Standards Institute accredited certifier to reduce lead, is effective in reducing lead exposures. Follow the instructions provided with the filter to ensure the filter is used properly. Use only cold water for drinking, cooking, and making baby formula. Boiling water does not remove lead from water. Before using tap water for drinking, cooking, or making baby formula, flush your pipes for several minutes. You can do this by running your tap, taking a shower, doing laundry or a load of dishes. If you have a lead service line or galvanized requiring replacement service line, you may need to flush your pipes for a longer period. If you are concerned about lead in your water and wish to have your water tested, contact the Utilities Department at 951-736-2276. Information on lead in drinking water, testing methods, and steps you can take to minimize exposure is available at https://www.epa.gov/safewater/lead.

Primary Standards – Mandatory Health-Related Standards

CLARITY                                          Please see pages 20-22 for key to abbreviations and footnotes

PARAMETER

UNITS

STATE MCL [MRDL]

PHG (MCLG) [MRDLG]

STATE DLR/ CCRDL(RL)

RANGE AVERAGE

WATER SOURCE

MAJOR SOURCES IN DRINKING WATER

Combined Filter Effluent Turbidity

%

95(a)

NA

–

% < 0.3

100%

Metropolitan Water District Henry  J. Mills Water Treatment Plant

Soil runoff

NTU

TT 0.3

Highest

0.07

Combined Filter Effluent Turbidity

%

95(a)

NA

–

% < 0.3

100%

City of Corona, Lester  & Sierra Del Oro Water Treatment Facilities

Soil runoff

NTU

TT 0.3

Highest

0.05

MICROBIOLOGICAL CONTAMINANTS

PARAMETER

UNITS

STATE MCL [MRDL]

PHG (MCLG) [MRDLG]

STATE DLR/ CCRDL(RL)

RANGE AVERAGE

REGULATED IN DISTRIBUTION SYSTEM

MAJOR SOURCES IN DRINKING WATER

Total Coliform Bacteria (State Total Coliform Rule)

%

5.0 (b)

(0)

–

–

Highest % of positive samples collected in any one  month = 0%

Naturally present in the  environment

Fecal Coliform and E. Coli (State Total Coliform Rule)

(c)

(c)

(0)

–

–

Total number of positive samples collected in 2025 = 0

Human and animal  fecal waste

Total Coliform Bacteria (Federal Total Coliform Rule)

%

TT (d)

–

–

–

Highest % of positive samples collected in any one  month = 0%

Naturally present in the  environment

Fecal Coliform and E. Coli (Federal Total Coliform Rule)

(e)

(e)

(0)

–

–

Total number of positive samples collected in 2025 = 0

Human and animal  fecal waste

Heterotrophic Plate Count (HPC)

CFU/mL

TT

NA

NA

Range

Distribution System  Wide: ND-22

Naturally present in the environment

Average

Distribution System  Wide: ND

RADIOACTIVE CONTAMINANTS (f)

PARAMETER

UNITS

STATE MCL [MRDL]

PHG (MCLG) [MRDLG]

STATE DLR/ CCRDL(RL)

RANGE AVERAGE

STATE PROJECT WATER

COLORADO RIVER WATER

GROUND WATER

TREATED AVERAGE SYSTEM WATER

MAJOR SOURCES IN DRINKING WATER

Gross Alpha  Particle Activity (k)

pCi/L

15

(0)

3

Range

ND

ND  - 3.2

ND  - 16.5

–

Erosion of natural deposits

Average

ND

5.41

Uranium

pCi/L

20

0.43

1

Range

ND

2.8 - 3.1

ND  - 20

–

Erosion of natural deposits

Average

2.9

5.85

Primary Standards – (continued)

INORGANIC CONTAMINANTS

PARAMETER

UNITS

STATE MCL [MRDL]

PHG (MCLG) [MRDLG]

STATE DLR/ CCRDL(RL)

RANGE AVERAGE

STATE PROJECT WATER

COLORADO RIVER WATER

GROUND WATER

TREATED AVERAGE SYSTEM WATER

MAJOR SOURCES IN DRINKING WATER

Arsenic

µg/L

10

0.004

2

Range

ND

2.1

ND - 13

ND - 2

Erosion of natural deposits; runoff from orchards; glass and electronics production wastes

Average

ND

ND

Barium

mg/L

1

2

0.1

Range

ND

0.13

ND - 0.19

ND - 0.13

Discharges of oil drilling  wastes and from metal refineries; erosion of natural deposits

Average

ND

ND

Chromium (hexavalent)

µg/L

10

0.02

0.1

Range

ND

ND

ND - 3.3

ND - .59

Erosion of natural deposits; transformation of naturally occurring trivalent chromium to hexavalent chromium by natural processes and human activities such as discharges from electroplating factories, leather tanneries, wood preservation, chemical synthesis, refractory production, and textile manufacturing facilities.

Average

0.7

0.2

Fluoride (e, h)

mg/L

2.0

1

0.1

Range

0.6 -  0.9

0.3

0.27 -  0.72

ND - 0.73

Erosion of natural deposits; water additive that promotes strong teeth;  discharge from fertilizer and aluminum factories

Average

0.7

0.4

0.23

Nitrate (as Nitrogen) (k, t)

mg/L

10

(as N)

10

(as N)

0.4

Range

ND

ND

ND - 20

ND - 6

Runoff and leaching from fertilizer use; leaching from septic  tanks and sewage; erosion of natural deposits

Average

9.8

2.3

Perchlorate (k, s)

µg/L

6

1

1

Range

ND

ND

ND - 9

ND - 2.8

Perchlorate is an inorganic chemical used in solid rocket propellant,  fireworks, explosives, flares, matches, and a variety of industries. It usually gets into drinking water as a result of environmental contamination from historic

aerospace or other industrial operations that used  or use, store, or dispose of perchlorate and its salts.

Average

3.4

ND

Selenium

µg/L

6

1

1

Range

ND

ND

ND - 7.8

ND

Discharge from  petroleum, glass, and metal refineries; ero-sion of natural deposits; discharge from mines and chemi-cal manufacturers; runoff  from livestock lots (feed additive)

Primary Standards – (continued)

SYNTHETIC ORGANIC CONTAMINANTS including Pesticides/PCBs

PARAMETER

UNITS

STATE MCL [MRDL]

PHG (MCLG) [MRDLG]

STATE DLR/ CCRDL(RL)

RANGE AVERAGE

STATE PROJECT WATER

COLORADO RIVER WATER

GROUND WATER

TREATED AVERAGE SYSTEM WATER

MAJOR SOURCES IN DRINKING WATER

1,2,3-Trichloropropane (1,2,3-TCP)(k, s, t)

µg/L

0.005

0.0007

0.005

Range

ND

ND

ND - 0.014

ND

Discharge from industrial and agricultural chemical factories; leaching from hazardous waste sites; used as cleaning and maintenance solvent, paint and varnish remover, and cleaning and degreasing agent; by-product during the production of other compounds and pesticides.

Average

ND

VOLATILE ORGANIC CONTAMINANTS

Tetrachloroethylene (PCE)

µg/L

5

0.06

0.5

Trichloroethylene (TCE)

µg/L

5

1.7

0.5

Secondary Standards– Aesthetic Standards

PARAMETER

UNITS

STATE MCL [MRDL]

PHG (MCLG) [MRDLG]

STATE DLR/ CCRDL(RL)

RANGE AVERAGE

STATE PROJECT WATER

COLORADO RIVER WATER

GROUND WATER

TREATED AVERAGE SYSTEM WATER

MAJOR SOURCES IN DRINKING WATER

Aluminum (i)

µg/L

200

600

50

Range

ND  - 96

ND

ND

ND  - 230

Erosion of natural  deposits; residual from  some surface water treatment processes

Max RAA

ND

100

Chloride

mg/L

500

NA

(2)

Range

55  - 59

101  - 102

110  - 260

17  - 110

Runoff/leaching from natural  deposits; sea water influence

Average

57

102

174

66

Color

units

15

NA

(1)

Range

1

2 - 3

ND  - 60

ND

Naturally-occurring organic materials

Average

2

4

Corrosivity

(as  Aggressiveness Index)

AI

NA

NA

NA

Range

12.1 - 12.3

–

12  - 13

8.9 - 13

Elemental balance in water; affected by temperature, other factors

Average

12.2

13

12

Foaming Agents –

Methylene Blue Active Substances (MBAS)

µg/L

500

NA

(50)

Range

ND

ND

ND - 280

ND - 130

Municipal and industrial waste discharges

Average

57

43

Iron (k)

µg/L

300

NA

100

Range

ND

ND

ND - 3400

ND

Leaching from natural deposits; industrial wastes

Average

243

Secondary Standards – Aesthetic Standards – (continued)

PARAMETER

UNITS

STATE MCL [MRDL]

PHG (MCLG) [MRDLG]

STATE DLR/ CCRDL(RL)

RANGE AVERAGE

STATE PROJECT WATER

COLORADO RIVER WATER

GROUND WATER

TREATED AVERAGE SYSTEM WATER

MAJOR SOURCES IN DRINKING WATER

Manganese (k)

µg/L

50

NL=500

(5)

Range

ND

ND

ND - 620

ND

Leaching from natural deposits

Average

63

Odor Threshold

Units

3

NA

1

Range

ND

4

ND - 2

ND - 1

Naturally-occurring organic materials

Average

ND

ND

Specific Conductance (k)

µS/cm

1,600

NA

NA

Range

386 - 422

990 - 1,030

1,200 - 1,800

84 - 1,053

Substances that form ions when in water; seawater influence

Average

404

1,010

1,431

630

Sulfate

mg/L

500

NA

0.5

Range

25 - 38

221 - 229

160 - 260

3.2 - 220

Runoff/leaching from natural deposits; industrial wastes

Average

32

225

207

109

Total Dissolved Solids (j, k, s)

mg/L

1,000

NA

(2)

Range

214 - 241

639 - 668

720 - 1,200

46 - 650

Runoff/leaching from natural deposits

Average

228

654

917

385

Turbidity

NTU

5

NA

0.1

Range

ND

0.9 - 1.4

0.1 - 26

0.1 - 0.3

Soil runoff

Average

1.1

2

0.17

Zinc

mg/L

5

NA

0.05

Range

ND

ND

ND - 6

ND

Soil runoff

Average

0.4

Perfluoroalkyl and Polyfluoroalkyl Substances (PFAS) with Notification Levels, Analyzed by EPA Methods 533 (s)

PARAMETER

UNITS

STATE MCL [MRDL]

PHG (MCLG) [MRDLG]

STATE DLR/ CCRDL(RL)

RANGE AVERAGE

STATE PROJECT WATER

COLORADO RIVER WATER

GROUND WATER

TREATED AVERAGE SYSTEM WATER

HEALTH EFFECTS

Perfluorobutane Sulfonic (PFBS)

ng/L

NL=500

NA

3

Range

ND

ND

2.9 - 43

ND

Industrial chemical factory discharges; runoff/leaching from landfills; used in fire-retarding foams and various industrial processes

Average

20

Perfluorohexane Sulfonic Acid  (PFHxS)

ng/L

NL=3

NA

3

Range

ND

ND

ND  - 50

ND

Average

22

Perfluorooctanoic Acid (PFOA)

ng/L

NL=5.1

0.007

4

Range

ND

ND

ND  - 220

ND

Average

76

Perfluorooctanesulfonate Acid  (PFOS)

ng/L

NL=6.5

1

4

Range

ND

ND

ND  - 330

ND

Average

98

Unregulated Contaminants with No MCLs (g)

PARAMETER

UNITS

STATE MCL [MRDL]

PHG (MCLG) [MRDLG]

STATE DLR/ CCRDL(RL)

RANGE AVERAGE

STATE PROJECT WATER

COLORADO RIVER WATER

GROUND WATER

TREATED AVERAGE SYSTEM WATER

HEALTH EFFECTS

Boron (p)

mg/L

NL=1

NA

0.1

Range

0.12

0.14

0.3 - 0.52

0.07 - 0.28

Boron exposures resulted in decreased fetal weight (developmental effects) in newborn rats.

Average

0.42

0.21

Vanadium

µg/L

NL=50

NA

3

Range

ND

ND

3 - 17

ND - 3.3

Vanadium exposures resulted in developmental and reproductive effects in rats.

Average

6.77

ND

Disinfection By-products, Disinfectant Residuals, and Disinfection By-product Precursors Federal Rule (m)

PARAMETER

UNITS

STATE MCL [MRDL]

PHG (MCLG) [MRDLG]

STATE DLR

RANGE AVERAGE/ LRAA/RAA

DISTRIBUTION SYSTEM WIDE

MAJOR SOURCES IN DRINKING WATER

HEALTH EFFECTS LANGUAGE

Total Trihalomethanes (TTHMs) (n)

µg/L

80

NA

1

Range

6.5 - 63

By-product of drinking water disinfection

Some people who drink water containing trihalomethanes in excess of the MCL over many years may experience liver, kidney, or central nervous system problems, and may have an increased risk of getting cancer.

LRAA

38.8

Haloacetic Acids (HAA5) (o)

µg/L

60

NA

1

Range

ND  - 11

By-product of drinking water disinfection

Some people who drink water containing haloacetic acids in excess of the MCL over many years may have an increased risk of getting cancer.

LRAA

9.9

Bromate (Mills - WR-24  Conn.) (l)

µg/L

10

0.1

1

Range

ND  - 5.6

Byproduct of drinking water disinfection

Some people who drink water containing bromate in excess of the MCL over many years may have an increased risk of getting cancer.

Max RAA

3

Chloramines

mg/L

[4 as Cl2]

[4 as Cl2]

NA

Range

1.03 - 2.82

Drinking water disinfectant added for treatment

Some people who use water containing chloramines well in excess of the MRDL could experience irritating effects to their eyes and nose. Some people who drink water containing chloramines well in excess of the MRDL could experience stomach discomfort or anemia.

Max RAA

1.98

Control of DBP precursors (TOC)

mg/L

TT

NA

0.3

Range

2.3 - 2.6

Various natural and manmade sources

Total organic carbon (TOC) has no health effects. However, total organic carbon provides a medium for the formation of disinfection byproducts. These byproducts include trihalomethanes (THMs) and haloacetic acids (HAAs).

Drinking water containing these byproducts in excess of the MCL may lead to adverse health effects, liver or kidney problems, or nervous system effects, and may lead to an increased risk of cancer.

Other Parameters

CHEMICAL

UNITS

STATE MCL [MRDL]

PHG (MCLG) [MRDLG]

STATE DLR/ CCRDL(RL)

RANGE AVERAGE

STATE PROJECT WATER

COLORADO RIVER WATER

GROUND WATER

TREATED AVERAGE SYSTEM WATER

Alkalinity

mg/L

NA

NA

(1)

Range

68 - 77

121 - 132

160 - 380

13 - 120

Average

72

126

246

83

Bicarbonate

mg/L

NA

NA

NA

Range

–

-

160 - 380

14 - 120

Average

246

82

Calcium

mg/L

NA

NA

(0.1)

Range

16 - 20

67 - 75

84 - 160

1.5 - 75

Average

18

71

127

40

Hardness (q)

mg/L

NA

NA

(1)

Range

82 - 94

279 - 298

290 - 570

7.2 - 290

Average

88

288

452

146

Magnesium

mg/L

NA

NA

(0.01)

Range

9.7 -11

26 - 27

20 - 46

0.39 - 25

Average

10

26

33

14

pH

pH Units

NA

NA

NA

Range

8.7

8.0 - 8.4

7.7 - 8.2

7.5 - 9.8

Average

8.2

7.9

8.2

Potassium

mg/L

NA

NA

(0.2)

Range

2.3 - 2.5

5.1 - 5.2

1.9 - 15

ND - 5

Average

2.4

5.2

5.4

3.2

Sodium (r)

mg/L

NA

NA

(1)

Range

45 - 47

97 - 99

54 - 180

19 - 97

Average

46

98

123

63

Water-saving Tip: Save up to 150 gallons a month by turning off the water while washing your hair.

Federal Unregulated Contaminants Monitoring Rule (UCMR 4) (u)

HALOACTIC ACID (HAA) GROUP

PARAMETER

UNITS

STATE MCL [MRDL]

PHG (MCLG) [MRDLG]

STATE DLR/ CCRDL(RL)

RANGE AVERAGE

DISTRIBUTION SYSTEM

HAA5 (o)

µg/L

NA

NA

NA

Range

ND-15.8

Average

5.9

HAA6Br (w)

µg/L

NA

NA

NA

Range

ND-17.3

Average

6.1

HAA9 (x)

µg/L

NA

NA

NA

Range

ND-28

Average

10.2

Total Organic Carbon

µg/L

NA

NA

NA

Range

ND-2,600

Average

1,925

Bromide

µg/L

NA

NA

NA

Range

ND-32

Average

15.3

METALS AND METALLOIDS GROUP

Manganese

µg/L

NA

NA

NA

Range

ND-62

Average

2

Federal Unregulated Contaminants Monitoring Rule (UCMR 5) (v)

LITHIUM BY ICP

PARAMETER

UNITS

STATE MCL [MRDL]

PHG (MCLG) [MRDLG]

STATE DLR/ CCRDL(RL)

RANGE AVERAGE

DISTRIBUTION SYSTEM

Lithium

µg/L

NA

NA

9

Range

ND-55.1

Average

16

EPA 533

PFBA

µg/L

NA

NA

0.005

Range

ND-0.0076

Average

ND

PFHxA

µg/L

NA

NA

0.003

Range

ND-0.0038

Average

ND

PFHxS

µg/L

NA

NA

0.003

Range

ND-0.0033

Average

ND

PFPeA

µg/L

NA

NA

0.003

Range

ND-0.0061

Average

ND

Key to Abbreviations

AI         Aggressiveness Index

CCDLP  Consumer Confidence Report Detection Level

CFU/mL Colony-Forming Units per Milliliter

DBP     Disinfection By-products

DLR      Detection Limits for purposes of Reporting

LRAA   Locational Running Annual Average

MBAS   Methylene Blue Active Substances

mg/L     Milligrams per liter or parts per million (ppm)

N          Nitrogen

NA        Not Applicable

ND        Not Detected

ng/L      Nanograms per liter or parts per trillion (ppt)

NL        Notification Level

NTU      Nephelometric Turbidity Units

pCi/L    Pico Curies per liter

RAA     Running Annual Average

TOC      Total Organic Carbon

μg/L      Micrograms per liter or parts per billion (ppb)

μS/cm   microSiemen per centimeter; or micromho per centimeter (µmho/cm)

Extended Abbreviations

Maximum Contaminant Level (MCL): The highest level of acontaminant that is allowed in drinking water. Primary MCLs are set as close to the PHGs (or MCLGs) as is economically and technologically feasible. Secondary MCLs are set to protect the odor, taste and appearance of drinking water.

Maximum Contaminant Level Goal (MCLG): The level of a contaminant in drinking water below which there is no known or expected risk to health. MCLGs are set by the U.S. Environmental Protection Agency.

Public Health Goal (PHG): The level of a contaminant in drinking water below which there is no known or expected risk to health. PHGs are set by the California Environmental Protection Agency.

Primary Drinking Water Standard (PDWS): MCLs and MRDLs for contaminants that affect health along with their monitoring and reporting requirements, and water treatment requirements.

Maximum Residual Disinfectant Level (MRDL): The highest level of a disinfectant allowed in drinking water. There is convincing evidence that addition of a disinfectant is necessary for control of microbial contaminants.

Maximum Residual Disinfectant Level Goal (MRDLG): The level of a drinking water disinfectant below which there is no known or expected risk to health. MRDLGs do not reflect the benefits of the use of disinfectants to control microbial contaminants.

Regulatory Action Level (AL): The concentration of a contaminant which, if exceeded, triggers treatment or other requirements that a water system must follow.

Treatment Technique (TT): A required process intended to reduce the level of a contaminant in drinking water.

Footnotes

(a) The turbidity level of the filtered water shall be less than or equal to 0.3 NTU in 95% of the measurements taken each month and shall not exceed 1 NTU at any time. Turbidity, a measure of the cloudiness of the water, is an indicator of treatment performance. The averages and ranges of turbidity shown in the Secondary Standards were based on the treatment plant effluent.

(b) Total coliform MCLs: No more than 5.0% of the monthly samples may be total coliform-positive. Compliance is based on the combined distribution system sampling from all the treatment plants. In 2025, 1560 samples were analyzed and there were no positive detections for total coliform. The MCL was not violated.

(c) E. coli MCL: The occurrence of two consecutive total coliform-positive samples, one of which contains E. coli, constitutes an acute MCL violation. The MCL was not violated.

(d) Total coliform TT trigger, Level 1 assessments, and total coliform TT violations: More than 5.0% total coliform-positive samples in a month trigger Level 1 assessments. Failure to conduct assessments and correct findings within 30 days is a total coliform violation. No triggers, Level 1 assessments, or violations occurred.

(e) E. coli MCL and Level 2 TT triggers for assessments: Routine and repeat samples are total coliform-positive and either sample is E.coli-positive or system fails to collect all repeat samples following an E.coli-positive sample, or fails to test for E. coli when the repeat sample is total coliform-positive. No samples were E. coli-positive. No MCLs violations or no assessments occurred.

(f) Results included in this section range from 2017-2025.

(g) Unregulated contaminant monitoring helps the USEPA and the State Board determine where certain contaminants occur and whether the contaminants need to be regulated.

(h) City of Corona was in compliance with all provisions of the State’s Fluoridation System Requirements. This is part of the City of Corona’s blending plan to reduce the levels of fluoride being delivered to the consumer’s tap. Refer to the “Treated Average System Water” column for a more accurate representation of system water quality.

(i) Aluminum has a secondary standard limit. In 2025 the secondary standard limit was exceeded a tour Treatment Facility effluent. The Maximum Running Annual Average (Max RAA) was 134 ug/L, no consumer action is necessary since secondary standards for aluminum are established only for aesthetic effects (water color). We are continually calibrating our aluminum base coagulant to achieve the non-mandatory secondary standard limit of 200 ug/L.

(j) Total Dissolved Solids (TDS) is a measure of the total amount of all the materials that are dissolved in water. These minerals, both natural and anthropogenic (made by humans), are mainly inorganic solids, with a minor amount of organic material.

(k) Thisconstituent was detected at levels exceeding the MCL, results shown in bold. Please note that this water is blended with water from other sources to providecustomers with the highest quality drinking water.

(l) Reported from Mills Filtration Plant Metropolitan Water District (MWD). Mills MWD water is blended with other Corona water sources. Please note that this water is blended with water from other sources to provide customers with the highest quality drinking water.

(m) The City of Corona was in compliance with all provisions of the Stage 2 Disinfectants and Disinfection By-products Rules (D/DBP). Compliance was based on the locational running annual average (LRAA). The average reported reflects the highest TTHM and HAA5 LRAAs for the year.

(n) Total Trihalomethanes is the sum of bromodichloromethane, bromoform,chloroform, and dibromochloromethane.

(o) HAA5 is the sum of dichloroacetic acid, trichloroacetic acid, monobromoacetic acid,dibromoacetic acid, and monochloroacetic acid.

(p) The sources that were detected for Boron are all directed to the Temescal Desalter for reverse osmosis treatment. The treated water is monitored at the effluent of the facility which is represented in the “Treated Average System Water” column.

(q) Hardness is the sum of polyvalent cations present in the water, generally magnesium and calcium. The cations are usually naturally occurring.

(r) Sodium refers to the salt present in the water and is generally naturally occurring.

(s) Fluoride, nitrate, perchlorate, TDS, 1,2,3-TCP, PFOA, PFOS, PFBS and PFHxS are a part of Corona’s blending remediation plan to reduce the levels being delivered to the consumer’s tap. Refer to the “Treated Average System Water” column for a more accurate representation of system water quality.

(t) 1,2,3-TCP was monitored quarterly in Corona’s source and treated waters for the State’s initial monitoring requirement and continues to be monitored per our Blending Plan requirements.

(u) UCMR 4 sampling took place from 2018-2019. Minimum reporting levels areas stipulated in the Federal UCMR 4. Detected parameter results are included in the CCR.

(v) UCMR 5 sampling took place 2023-2024. Minimum reporting levels are as stipulated in the Federal UCMR 5. Detected parameter results are included in the CCR.

(w) HAA6Br: Bromochloroacetic acid, bromodichloroacetic acid, dibromoacetic acid,dibromochloroacetic acid, monobromoacetic acid, and tribromoacetic acid.

(x) HAA9: Bromochloroacetic acid, bromodichloroacetic acid, chlorodibromoacetic acid, dibromoacetic acid, dichloroacetic acid, monobromoacetic acid, monochloroacetic acid, tribromoacetic acid, and trichloroacetic acid.

Frequently Asked Questions

How hard is my water?

Hardness is dissolved minerals, including calcium and magnesium. This may cause a deposit or water spots on fixtures and dishes. Our average hardness in the system is 146 ppm or 8.5 grains per gallon, which is classified as hard. Our water hardness can change depending on the water demand and the season.

When I turn on my kitchen or bathroom faucet, the water comes out white. What is wrong?

Dissolved air in the water causes a milky appearance. When you turn on your faucet, the pressure is relieved and this allows the air to form bubbles that rise to the top of the glass. It will clear within a minute, beginning at the bottom of the glass. The water is safe to drink.

How do I flush my water heater?

We have general instructions for flushing your water heater; for specific instructions consult your user’s manual or look on the manufacturer’s website.

1. Turn the gas valve to “pilot.”

2. Hook up a garden hose to the water heater and find a proper location to drain the water; use caution – water will be hot when it comes out.

3. Open the valve until all of the hot water has drained from the water heater.

4. Close the valve where the garden hose is hooked up.

5. Allow the heater to fill up, and then close the cold water supply on top of the water heater.

6. Open up the hose bib again and let it drain.

7. Repeat the cycle a couple of times.

8. Disconnect the garden hose, turn the water supply back on and turn the gas valve to the “on” position.

My water pressure has been very high recently, what’s wrong?

The City has six separate water pressure zones. Your pressure should be constant throughout the day but may decrease 3 - 5 pounds when system demands go up, such as during the night when a lot of water is used for irrigation. If your pressure has suddenly increased, it may mean that your pressure regulator needs to be adjusted or replaced. Call us at (951) 736-2234 and we will be happy to help troubleshoot the issue for you.

There is an odor coming from my water, what’s wrong? Is the water safe to drink?

We sometimes receive phone calls from customers stating that their water smells. However, the source of the odor is usually not the water, but from something else in the home. To test this, simply fill a glass with water and smell it. If the water itself does not smell, but you still smell the odor, there could be another issue such as a sink that needs to have the garbage disposal cleaned or run. A front-loading washing machine can also develop an odor from mold if the lid remains closed.

Monitoring Requirements Notice

Our water system failed to monitor as required for drinking water standards duringthe past year and, therefore, was in violation of the regulations. Even though this failure was not an emergency, as our customers, you have a right to know what you should do, what happened, and what we did to correct this situation. We are required to monitor your drinking water for specific contaminants on a regular basis. Results of regular monitoring are an indicator of whether or not our drinking water meets health standards. During 2016-2025, we did not complete all the required monitoring at Standby Wells 03 and 21. We did not monitor for the following contaminants at Well 03: inorganic and organic chemicals, gross alpha particle activity, uranium, radium-226 and radium-228. We also did not monitor for the following contaminants at Standby Well 21: gross alpha particle activity, uranium, radium-226, radium-228, and 1,2,3-trichloropropane. These wells have been on Standby status since 2018 and were out-of-service previously, meaning they were not added or distributed to the water system. There is no action needed for consumers to take at this time. We have since taken the required samples in March 2026. Please share this information with all the other people who drink this water, especially those who may not have received this public notice directly (for example, people in apartments, nursing homes, schools, and businesses). You can do this by posting this publicnotice in a public place or distributing copies by hand or mail.

For more information, please contact Justin Amon at 951-736-2481 or Justin.Amon@CoronaCA.gov.

Standby Wells: Wells that do not contribute as a regular water supply source. Use of standby wells requires notification to the State Water Board and its status cannot be changed unless approved by the State Water Board.

To change the language of this report, please select thelanguage under “Translate” in the upper menu features found at www.CoronaCA.gov/departments/utilities/about-dwp/learn-more/publications.

Español: Para cambiar el idioma de este reporte,seleccione el idioma en “Translate” en las funciones del menú que se encuentraen: www.CoronaCA.gov/departments/utilities/about-dwp/learn-more/publications.

If you are interested in participating in decisions that affect the quality and supply of the water in the City of Corona, or for general information about this report and questions related to water quality, please call (951) 736-2234.

Regular City Council meetings are held on the first and third Wednesday of every month.

City of Corona

Utilities Department

755 Public Safety Way

Corona, CA 92878

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