Know Your Environment. Protect Your Health.

UTILITY

Town of Discovery Bay

location

Discovery Bay, California

serves

16,790

source

Groundwater

data

2013-2023

Overview

EWG's drinking water quality report shows results of tests conducted by the water utility and provided to the Environmental Working Group by the California State Water Resources Control Board, as well as information from the U.S. EPA Enforcement and Compliance History database (ECHO). For the latest quarter assessed by the U.S. EPA (April 2024 - June 2024), tap water provided by this water utility was in compliance with federal health-based drinking water standards.

Contaminants Detected

Arsenic

Potential Effect: cancer

This Utility: 1.60 ppb

400x

EWG's Health Guideline: 0.004 ppb

Arsenic

Arsenic is a potent carcinogen and common contaminant in drinking water. Arsenic causes thousands of cases of cancer each year in the U.S. Click here to read more about arsenic.

Arsenic was found at 400 times above EWG's Health Guideline.

EWG Health Guideline

0.004 ppb or less

This Utility

1.6 ppb

Legal Limit

10 ppb

National Average

0.624 ppb

State Average

0.899 ppb

Health Risks

The EWG Health Guideline of 0.004 ppb for arsenic was defined by the California Office of Environmental Health Hazard Assessment as a public health goal, the level of a drinking water contaminant that does not pose a significant health risk. This health guideline protects against cancer.

Understanding the Data

The state and national averages were calculated using the averages of the contaminant measurements for each utility in 2021-2023.

ppb = parts per billion

Pollution Sources

Agriculture

Industry

Naturally Occurring

Filtering Options

Reverse Osmosis

Ion Exchange

Bromodichloromethane

Potential Effect: cancer

This Utility: 4.58 ppb

76x

EWG's Health Guideline: 0.06 ppb

Bromodichloromethane

Bromodichloromethane, one of the total trihalomethanes (TTHMs), is formed when chlorine or other disinfectants are used to treat drinking water. Bromodichloromethane and other disinfection byproducts increase the risk of cancer and may cause problems during pregnancy. Click here to read more about disinfection byproducts.

Bromodichloromethane was found at 76 times above EWG's Health Guideline.

EWG Health Guideline

0.06 ppb or less

This Utility

4.58 ppb

National Average

5.89 ppb

State Average

5.64 ppb

Health Risks

The EWG Health Guideline of 0.06 ppb for bromodichloromethane was based on the California Office of Environmental Health Hazard Assessment's public health goal, the level of a drinking water contaminant that does not pose a significant health risk. This health guideline protects against cancer and harm to fetal growth and development.

Legal Limit

None

Understanding the Data

The state and national averages were calculated using the averages of the contaminant measurements for each utility in 2021-2023.

ppb = parts per billion

Pollution Sources

Treatment Byproducts

Filtering Options

Activated Carbon

Reverse Osmosis

Bromoform

Potential Effect: cancer

This Utility: 34.5 ppb

69x

EWG's Health Guideline: 0.5 ppb

Bromoform

Bromoform, one of the total trihalomethanes (TTHMs), is formed when chlorine or other disinfectants are used to treat drinking water. Bromoform and other disinfection byproducts increase the risk of cancer and may cause problems during pregnancy. Click here to read more about disinfection byproducts.

Bromoform was found at 69 times above EWG's Health Guideline.

EWG Health Guideline

0.5 ppb or less

This Utility

34.5 ppb

National Average

1.44 ppb

State Average

3.85 ppb

Health Risks

The EWG Health Guideline of 0.5 ppb for bromoform is based on the California Office of Environmental Health Hazard Assessment's public health goal, the level of a drinking water contaminant that does not pose a significant health risk. This health guideline protects against cancer, harm to reproduction and child development, and change to fetal growth and development .

Legal Limit

None

Understanding the Data

The state and national averages were calculated using the averages of the contaminant measurements for each utility in 2021-2023.

ppb = parts per billion

Pollution Sources

Treatment Byproducts

Filtering Options

Activated Carbon

Reverse Osmosis

Chloroform

Potential Effect: cancer

This Utility: 2.06 ppb

5.1x

EWG's Health Guideline: 0.4 ppb

Chloroform

Chloroform, one of the total trihalomethanes (TTHMs), is formed when chlorine or other disinfectants are used to treat drinking water. Chloroform and other disinfection byproducts increase the risk of cancer and may cause problems during pregnancy.

Chloroform was found at 5.1 times above EWG's Health Guideline.

EWG Health Guideline

0.4 ppb or less

This Utility

2.06 ppb

National Average

16.2 ppb

State Average

10.5 ppb

Health Risks

The EWG Health Guideline of 0.4 ppb for chloroform was based on the California Office of Environmental Health Hazard Assessment's public health goal, the level of a drinking water contaminant that does not pose a significant health risk. This health guideline protects against cancer and harm to fetal growth and development.

Legal Limit

None

Understanding the Data

The state and national averages were calculated using the averages of the contaminant measurements for each utility in 2021-2023.

ppb = parts per billion

Pollution Sources

Treatment Byproducts

Filtering Options

Activated Carbon

Reverse Osmosis

Dibromoacetic acid

Potential Effect:

This Utility: 10.1 ppb

338x

EWG's Health Guideline: 0.03 ppb

Dibromoacetic acid

Dibromoacetic acid, one of the group of five haloacetic acids regulated by federal standards, is formed when chlorine or other disinfectants are used to treat drinking water. Haloacetic acids and other disinfection byproducts increase the risk of cancer and may cause problems during pregnancy. Click here to read more about disinfection byproducts.

Dibromoacetic acid was found at 338 times above EWG's Health Guideline.

EWG Health Guideline

0.03 ppb or less

This Utility

10.1 ppb

National Average

1.13 ppb

State Average

1.94 ppb

Health Risks

The EWG Health Guideline of 0.03 ppb for dibromoacetic acid was defined by the California Office of Environmental Health Hazard Assessment's public health goal, the level of a drinking water contaminant that does not pose a significant health risk. This health guideline protects against cancer and harm to fetal growth and development.

Legal Limit

None

Understanding the Data

The state and national averages were calculated using the averages of the contaminant measurements for each utility in 2021-2023.

ppb = parts per billion

Pollution Sources

Treatment Byproducts

Filtering Options

Activated Carbon

Reverse Osmosis

Dibromochloromethane

Potential Effect: cancer

This Utility: 12.1 ppb

121x

EWG's Health Guideline: 0.1 ppb

Dibromochloromethane

Dibromochloromethane, one of the total trihalomethanes (TTHMs), is formed when chlorine or other disinfectants are used to treat drinking water. Dibromochloromethane and other disinfection byproducts increase the risk of cancer and may cause problems during pregnancy. Click here to read more about disinfection byproducts.

Dibromochloromethane was found at 121 times above EWG's Health Guideline.

EWG Health Guideline

0.1 ppb or less

This Utility

12.1 ppb

National Average

3.55 ppb

State Average

6.38 ppb

Health Risks

The EWG Health Guideline of 0.1 ppb for dibromochloromethane was based on the California Office of Environmental Health Hazard Assessment's public health goal, the level of a drinking water contaminant that does not pose a significant health risk. This health guideline protects against cancer and harm to fetal growth and development.

Legal Limit

None

Understanding the Data

The state and national averages were calculated using the averages of the contaminant measurements for each utility in 2021-2023.

ppb = parts per billion

Pollution Sources

Treatment Byproducts

Filtering Options

Activated Carbon

Reverse Osmosis

Dichloroacetic acid

Potential Effect: cancer

This Utility: 1.000 ppb

5x

EWG's Health Guideline: 0.2 ppb

Dichloroacetic acid

Dichloroacetic acid, one of the group of five haloacetic acids regulated by federal standards, is formed when chlorine or other disinfectants are used to treat drinking water. Haloacetic acids and other disinfection byproducts increase the risk of cancer and may cause problems during pregnancy. Click here to read more about disinfection byproducts.

Dichloroacetic acid was found at 5 times above EWG's Health Guideline.

EWG Health Guideline

0.2 ppb or less

This Utility

1 ppb

National Average

8 ppb

State Average

4.69 ppb

Health Risks

The EWG Health Guideline of 0.2 ppb for dichloroacetic acid was defined by the California Office of Environmental Health Hazard Assessment's public health goal, the level of a drinking water contaminant that does not pose a significant health risk. This health guideline protects against cancer and harm to reproduction and child development.

Legal Limit

None

Understanding the Data

The state and national averages were calculated using the averages of the contaminant measurements for each utility in 2021-2023.

ppb = parts per billion

Pollution Sources

Treatment Byproducts

Filtering Options

Activated Carbon

Reverse Osmosis

Haloacetic acids (HAA5)

Potential Effect: cancer

This Utility: 36.2 ppb

362x

EWG's Health Guideline: 0.1 ppb

Haloacetic acids (HAA5)

Haloacetic acids are formed when disinfectants such as chlorine are added to tap water. The group of five haloacetic acids regulated by federal standards includes monochloroacetic acid, dichloroacetic acid, trichloroacetic acid, monobromoacetic acid and dibromoacetic acid.

Haloacetic acids (HAA5) was found at 362 times above EWG's Health Guideline.

EWG Health Guideline

0.1 ppb or less

This Utility

36.2 ppb

Legal Limit

60 ppb

National Average

19.8 ppb

State Average

35.5 ppb

Health Risks

The EWG Health Guideline of 0.1 ppb for the group of five haloacetic acids, or HAA5, was defined in a peer-reviewed scientific study by EWG and represents a one-in-a-million lifetime cancer risk level. This health guideline protects against cancer.

Understanding the Data

The state and national averages were calculated using the averages of the contaminant measurements for each utility in 2021-2023.

ppb = parts per billion

Pollution Sources

Treatment Byproducts

Filtering Options

Activated Carbon

Reverse Osmosis

Haloacetic acids (HAA9)

Potential Effect: cancer

This Utility: 22.5 ppb

376x

EWG's Health Guideline: 0.06 ppb

Haloacetic acids (HAA9)

Haloacetic acids are formed when disinfectants such as chlorine are added to tap water. The group of nine haloacetic acids includes monochloroacetic acid, dichloroacetic acid, trichloroacetic acid, monobromoacetic acid and dibromoacetic acid, which are regulated as a group by the federal government (HAA5); and bromochloroacetic acid, bromodichloroacetic acid, chlorodibromoacetic acid, and tribromoacetic acid.

Haloacetic acids (HAA9) was found at 376 times above EWG's Health Guideline.

EWG Health Guideline

0.06 ppb or less

This Utility

22.5 ppb

National Average

23.7 ppb

State Average

15.5 ppb

Health Risks

The EWG Health Guideline of 0.06 ppb for the group of nine haloacetic acids, or HAA9, was defined in a peer-reviewed scientific study by EWG and represents a one-in-a-million lifetime cancer risk level as . This health guideline protects against cancer.

Legal Limit

None

Understanding the Data

The state and national averages were calculated using the averages of the contaminant measurements for each utility in 2018-2021.

ppb = parts per billion

Pollution Sources

Treatment Byproducts

Filtering Options

Activated Carbon

Reverse Osmosis

Total trihalomethanes (TTHMs)

Potential Effect: cancer

This Utility: 53.3 ppb

355x

EWG's Health Guideline: 0.15 ppb

Total trihalomethanes (TTHMs)

Trihalomethanes are cancer-causing contaminants that form during water treatment with chlorine and other disinfectants. The total trihalomethanes group includes four chemicals: chloroform, bromodichloromethane, dibromochloromethane and bromoform.

Total trihalomethanes (TTHMs) was found at 355 times above EWG's Health Guideline.

EWG Health Guideline

0.15 ppb or less

This Utility

53.3 ppb

Legal Limit

80 ppb

National Average

29.1 ppb

State Average

27.1 ppb

Health Risks

The health guideline of 0.15 parts per billion, or ppb, for the group of four trihalomethanes, or THM4/TTHM, was defined in a peer-reviewed scientific study by EWG and represents a one-in-one-million lifetime cancer risk level.

Understanding the Data

The state and national averages were calculated using the averages of the contaminant measurements for each utility in 2021-2023.

ppb = parts per billion

Pollution Sources

Treatment Byproducts

Filtering Options

Activated Carbon

Reverse Osmosis

Trichloroacetic acid

Potential Effect: cancer

This Utility: 1.06 ppb

11x

EWG's Health Guideline: 0.1 ppb

Trichloroacetic acid

Trichloroacetic acid, one of the group of five haloacetic acids regulated by federal standards, is formed when chlorine or other disinfectants are used to treat drinking water. Haloacetic acids and other disinfection byproducts increase the risk of cancer and may cause problems during pregnancy. Click here to read more about disinfection byproducts.

Trichloroacetic acid was found at 11 times above EWG's Health Guideline.

EWG Health Guideline

0.1 ppb or less

This Utility

1.06 ppb

National Average

6.57 ppb

State Average

3.71 ppb

Health Risks

The EWG Health Guideline of 0.1 ppb for trichloroacetic acid was defined by the California Office of Environmental Health Hazard Assessment's public health goal, the level of a drinking water contaminant that does not pose a significant health risk. This health guideline protects against cancer and harm to reproduction and child development.

Legal Limit

None

Understanding the Data

The state and national averages were calculated using the averages of the contaminant measurements for each utility in 2021-2023.

ppb = parts per billion

Pollution Sources

Treatment Byproducts

Filtering Options

Activated Carbon

Reverse Osmosis

Uranium

Potential Effect: cancer

This Utility: 1.86 pCi/L

4.3x

EWG's Health Guideline: 0.43 pCi/L

Uranium

Uranium is a known human carcinogen. The federal legal limit for uranium is set at 30 micrograms per liter (corresponding to parts per billion), but utilities can also report uranium in picocuries per liter (pCi/L), which is a measure of radioactivity in water. EWG translated all uranium results to pCi/L using a conversion factor developed by the EPA. With this conversion approach, the limit of 30 ppb corresponds to 20 pCi/L. Drinking water with this much uranium would cause more than 4.6 cancer cases in a population of 100,000. California set a public health goal for uranium of 0.43 pCi/L.

Uranium was found at 4.3 times above EWG's Health Guideline.

EWG Health Guideline

0.43 pCi/L or less

This Utility

1.86 pCi/L

Legal Limit

20 pCi/L

National Average

1.03 pCi/L

State Average

1.91 pCi/L

Health Risks

The EWG Health Guideline of 0.43 pCi/L for uranium was defined by the California Office of Environmental Health Hazard Assessment as a public health goal, the level of a drinking water contaminant that does not pose a significant health risk. Three most common uranium isotopes are U-234, U-235 and U-238. All isotopes of uranium are radioactive, and the total radioactivity depends on the ratio of isotopes. This health guideline protects against cancer.

Understanding the Data

The state and national averages were calculated using the averages of the contaminant measurements for each utility in 2018-2023.

pCi/L = picocuries per liter

Pollution Sources

Industry

Naturally Occurring

Filtering Options

Reverse Osmosis

Ion Exchange

Includes chemicals detected in 2021-2023 for which annual utility averages exceeded an EWG-selected health guideline established by a federal or state public health authority; radiological contaminants detected between 2018 and 2023.

† HAA5 is a contaminant group that includes monochloroacetic acid, dichloroacetic acid, trichloroacetic acid, monobromoacetic acid and dibromoacetic acid. HAA9 is a contaminant group that includes the chemicals in HAA5 and bromochloroacetic acid, bromodichloroacetic acid, chlorodibromoacetic acid and tribromoacetic acid. TTHM is a contaminant group that includes bromodichloromethane, bromoform, chloroform and dibromochloromethane.

Aluminum

This Utility: 14.0 ppb

EWG's Health Guideline: 600 ppb

Aluminum

Aluminum is a metal released from metal refineries and mining operations. Too much aluminum exposure can impair children's brain development.

How your levels compare

EWG Health Guideline

600 ppb or less

This Utility

14 ppb

National Average

26.4 ppb

State Average

30.7 ppb

Health Risks

The EWG Health Guideline of 600 ppb for aluminum was defined by the California Office of Environmental Health Hazard Assessment as a public health goal, the level of a drinking water contaminant that does not pose a significant health risk. This health guideline protects against harm to the brain and nervous system.

Legal Limit

None

Understanding the Data

The state and national averages were calculated using the averages of the contaminant measurements for each utility in 2021-2023.

ppb = parts per billion

Pollution Sources

Industry

Naturally Occurring

Filtering Options

Reverse Osmosis

Barium

This Utility: 73.4 ppb

EWG's Health Guideline: 700 ppb

Barium

Barium is a mineral present in rocks, soil and water. High concentrations of barium in drinking water increase the risk of cardiovascular disease and hypertension.

How your levels compare

EWG Health Guideline

700 ppb or less

This Utility

73.4 ppb

Legal Limit

2,000 ppb

National Average

39.5 ppb

State Average

31 ppb

Health Risks

The EWG Health Guideline of 700 ppb for barium was defined by EWG as benchmark that protects against harm to the kidneys and the cardiovascular system.

Understanding the Data

The state and national averages were calculated using the averages of the contaminant measurements for each utility in 2021-2023.

ppb = parts per billion

Pollution Sources

Industry

Naturally Occurring

Filtering Options

Reverse Osmosis

Ion Exchange

Chlorate

This Utility: 196.3 ppb

EWG's Health Guideline: 210 ppb

Chlorate

Chlorate forms in drinking water as a byproduct of disinfection. Chlorate impairs thyroid function, making chlorate exposure most harmful during pregnancy and childhood.

How your levels compare

EWG Health Guideline

210 ppb or less

This Utility

196.3 ppb

National Average

116.8 ppb

State Average

127.9 ppb

Health Risks

The EWG Health Guideline of 210 ppb for chlorate was defined by the Environmental Protection Agency as a benchmark for testing under the Unregulated Contaminant Monitoring Rule program. This health guideline protects against hormone disruption.

Legal Limit

None

Understanding the Data

The state and national averages were calculated using the averages of the contaminant measurements for each utility in 2013-2023.

ppb = parts per billion

Pollution Sources

Agriculture

Industry

Treatment Byproducts

Chromium (hexavalent)

This Utility: 0.00194 ppb

EWG's Health Guideline: 0.02 ppb

Chromium (hexavalent)

Chromium (hexavalent) is a carcinogen that commonly contaminates American drinking water. Chromium (hexavalent) in drinking water may be due to industrial pollution or natural occurrences in mineral deposits and groundwater. Read more about chromium (hexavalent).

How your levels compare

EWG Health Guideline

0.02 ppb or less

This Utility

0.00194 ppb

National Average

0.44 ppb

State Average

0.812 ppb

Health Risks

The EWG Health Guideline of 0.02 ppb for chromium (hexavalent) was defined by the California Office of Environmental Health Hazard Assessment as a public health goal, the level of a drinking water contaminant that does not pose a significant health risk. This health guideline protects against cancer.

Legal Limit

None

Understanding the Data

The state and national averages were calculated using the averages of the contaminant measurements for each utility in 2013-2023.

ppb = parts per billion

Pollution Sources

Industry

Naturally Occurring

Filtering Options

Reverse Osmosis

Ion Exchange

Fluoride

This Utility: 0.280 ppm

No EWG Health Guideline

Fluoride

Fluoride occurs naturally in surface and groundwater and is also added to drinking water by many water systems to prevent cavities and support oral health in people.

In 2015, the Department of Health and Human Services updated its recommendation of an optimal level of 0.7 parts per million, or ppm, added to drinking water based on the health benefits of tooth decay prevention. Studies have shown that fluoride added to community water systems at this level reduces dental cavities, especially in children.

And studies have conclusively shown that fluoride in toothpaste and mouthwash can also provide these benefits.

How your levels compare

This Utility

0.28 ppm

Legal Limit

4 ppm

National Average

0.49 ppm

State Average

0.47 ppm

EWG Health Guideline

Not yet determined

Understanding the Data

The state and national averages were calculated using the averages of the contaminant measurements for each utility in 2021-2023.

ppm = parts per million

Pollution Sources

Industry

Treatment Byproducts

Naturally Occurring

Filtering Options

Reverse Osmosis

Lithium

This Utility: 23.3 ppb

No EWG Health Guideline

Lithium

Lithium occurs naturally in soil and rock. It is a pollutant from mining and industrial manufacturing of metals, ceramics and batteries. Ingesting too much lithium can lead to symptoms like abdominal pain, diarrhea, nausea and vomiting.

How your levels compare

This Utility

23.3 ppb

National Average

8.74 ppb

State Average

14.8 ppb

EWG Health Guideline

Not yet determined

Legal Limit

None

Understanding the Data

The state and national averages were calculated using the averages of the contaminant measurements for each utility in 2018-2024.

ppb = parts per billion

Pollution Sources

Industry

Runoff & Sprawl

Naturally Occurring

Filtering Options

Reverse Osmosis

Ion Exchange

Manganese

This Utility: 37.5 ppb

EWG's Health Guideline: 100 ppb

Manganese

Manganese is a naturally occurring element that is common in food and drinking water. Excessive manganese exposures may impair children's attention, memory and intellectual capacity. Click here to read more about manganese.

How your levels compare

EWG Health Guideline

100 ppb or less

This Utility

37.5 ppb

National Average

8.66 ppb

State Average

4.56 ppb

Health Risks

The EWG Health Guideline of 100 ppb for manganese was defined by the state of Minnesota as a health risk limit, the concentration of a contaminant that can be consumed with little or no risk to health. This health guideline protects against harm to the brain and nervous system.

Legal Limit

None

Understanding the Data

The state and national averages were calculated using the averages of the contaminant measurements for each utility in 2013-2023.

ppb = parts per billion

Pollution Sources

Industry

Naturally Occurring

Filtering Options

Ion Exchange

Molybdenum

This Utility: 3.45 ppb

EWG's Health Guideline: 40 ppb

Molybdenum

Molybdenum is a metal that occurs naturally in soil, minerals and water. People who ingest large amounts can have increased levels of uric acid and gout-like symptoms.

How your levels compare

EWG Health Guideline

40 ppb or less

This Utility

3.45 ppb

National Average

1.49 ppb

State Average

3.27 ppb

Health Risks

The EWG Health Guideline of 40 ppb for molybdenum was defined by the Environmental Protection Agency as a benchmark for testing under the Unregulated Contaminant Monitoring Rule program. This health guideline protects against metabolic changes and excess formation of uric acid in the blood.

Legal Limit

None

Understanding the Data

The state and national averages were calculated using the averages of the contaminant measurements for each utility in 2013-2023.

ppb = parts per billion

Pollution Sources

Industry

Naturally Occurring

Filtering Options

Reverse Osmosis

Ion Exchange

Monobromoacetic acid

This Utility: 0.806 ppb

EWG's Health Guideline: 25 ppb

Monobromoacetic acid

Monobromoacetic acid, one of the group of five haloacetic acids regulated by federal standards, is formed when chlorine or other disinfectants are used to treat drinking water. Haloacetic acids and other disinfection byproducts increase the risk of cancer and may cause problems during pregnancy. Click here to read more about disinfection byproducts.

How your levels compare

EWG Health Guideline

25 ppb or less

This Utility

0.806 ppb

National Average

0.18 ppb

State Average

0.128 ppb

Health Risks

The EWG Health Guideline of 25 ppb for monobromoacetic acid was defined by the California Office of Environmental Health Hazard Assessment's public health goal, the level of a drinking water contaminant that does not pose a significant health risk. This health guideline protects against change to fetal growth and development.

Legal Limit

None

Understanding the Data

The state and national averages were calculated using the averages of the contaminant measurements for each utility in 2021-2023.

ppb = parts per billion

Pollution Sources

Treatment Byproducts

Filtering Options

Activated Carbon

Reverse Osmosis

Monochloroacetic acid

This Utility: 0.0833 ppb

EWG's Health Guideline: 53 ppb

Monochloroacetic acid

Monochloroacetic acid, one of the group of five haloacetic acids regulated by federal standards, is formed when chlorine or other disinfectants are used to treat drinking water. Haloacetic acids and other disinfection byproducts increase the risk of cancer and may cause problems during pregnancy. Click here to read more about disinfection byproducts.

How your levels compare

EWG Health Guideline

53 ppb or less

This Utility

0.0833 ppb

National Average

0.497 ppb

State Average

0.161 ppb

Health Risks

The EWG Health Guideline of 53 ppb for monochloroacetic acid was defined by the California Office of Environmental Health Hazard Assessment's public health goal, the level of a drinking water contaminant that does not pose a significant health risk.a public health goal. This health guideline protects against change to fetal growth and development.

Legal Limit

None

Understanding the Data

The state and national averages were calculated using the averages of the contaminant measurements for each utility in 2021-2023.

ppb = parts per billion

Pollution Sources

Treatment Byproducts

Filtering Options

Activated Carbon

Reverse Osmosis

Selenium

This Utility: 3.60 ppb

EWG's Health Guideline: 30 ppb

Selenium

Selenium is an essential element in diets. But too much selenium can decrease thyroid hormone production and cause hair loss, skin lesions and brittle fingernails.

How your levels compare

EWG Health Guideline

30 ppb or less

This Utility

3.6 ppb

Legal Limit

50 ppb

National Average

0.29 ppb

State Average

0.298 ppb

Health Risks

The EWG Health Guideline of 30 ppb for selenium was defined by the California Office of Environmental Health Hazard Assessment as a public health goal, the level of a drinking water contaminant that does not pose a significant health risk. This health guideline protects against hair loss and nail damage.

Understanding the Data

The state and national averages were calculated using the averages of the contaminant measurements for each utility in 2021-2023.

ppb = parts per billion

Pollution Sources

Industry

Naturally Occurring

Filtering Options

Reverse Osmosis

Strontium

This Utility: 0.720 ppb

EWG's Health Guideline: 1,500 ppb

Strontium

Strontium is a metal that accumulates in the bones. Radioactive strontium-90 can cause bone cancer and leukemia, and any form of strontium at high doses can harm bone health.

How your levels compare

EWG Health Guideline

1,500 ppb or less

This Utility

0.72 ppb

National Average

0.488 ppb

State Average

0.695 ppb

Health Risks

The EWG Health Guideline of 1,500 ppb for strontium was defined by the Environmental Protection Agency as a benchmark for testing under the Unregulated Contaminant Monitoring Rule program. This health guideline protects against harm to bones.

Legal Limit

None

Understanding the Data

The state and national averages were calculated using the averages of the contaminant measurements for each utility in 2013-2023.

ppb = parts per billion

Pollution Sources

Industry

Naturally Occurring

Filtering Options

Reverse Osmosis

Ion Exchange

Vanadium

This Utility: 0.348 ppb

EWG's Health Guideline: 21 ppb

Vanadium

Vanadium is a metal used in steels and other alloys. People are commonly exposed to vanadium in water and food. Excessive exposure can be toxic during pregnancy and childhood.

How your levels compare

EWG Health Guideline

21 ppb or less

This Utility

0.348 ppb

National Average

1.54 ppb

State Average

3.25 ppb

Health Risks

The EWG Health Guideline of 21 ppb for vanadium was defined by the Environmental Protection Agency as a benchmark for testing under the Unregulated Contaminant Monitoring Rule program. This health guideline protects against change in blood chemistry.

Legal Limit

None

Understanding the Data

The state and national averages were calculated using the averages of the contaminant measurements for each utility in 2013-2023.

ppb = parts per billion

Pollution Sources

Industry

Naturally Occurring

Filtering Options

Ion Exchange

Includes chemicals detected in 2021-2023 for which annual utility averages were lower than an EWG-selected health guideline established by a federal or state public health authority.

Other Contaminants Tested

Chemicals tested for but not detected:

1,1,1,2-Tetrachloroethane, 1,1,1-Trichloroethane, 1,1,2,2-Tetrachloroethane, 1,1,2-Trichloroethane, 1,1-Dichloroethane, 1,1-Dichloroethylene, 1,1-Dichloropropene, 1,2,3-Trichlorobenzene, 1,2,3-Trichloropropane, 1,2,4-Trichlorobenzene, 1,2,4-Trimethylbenzene, 1,2-Dibromo-3-chloropropane (DBCP), 1,2-Dichloroethane, 1,2-Dichloropropane, 1,3,5-Trimethylbenzene, 1,3-Butadiene, 1,3-Dichloropropane, 1,3-Dichloropropene, 1,4-Dioxane, 1-butanol, 11-chloroeicosafluoro-3-oxaundecane-1-sulfonic aci, 2,2-Dichloropropane, 2,3,7,8-TCDD (Dioxin), 2,4,5-T, 2,4,5-TP (Silvex), 2,4-D, 2-methoxyethanol, 2-propen-1-ol, 3-Hydroxycarbofuran, 4,8-dioxa-3H-perfluorononanoic acid (ADONA), 4:2 Fluorotelomer Sulfonic Acid (4:2 FTSA), 6:2 Fluorotelomer Sulfonic Acid (6:2 FTSA), 8:2 Fluorotelomer Sulfonic Acid (8:2 FTSA), 9-chlorohexadecafluoro-3-oxanone-1-sulfonic acid (, Alachlor (Lasso), Aldicarb, Aldicarb sulfone, Aldicarb sulfoxide, Aldrin, Alpha-hexachlorocyclohexane, Antimony, Atrazine, Bentazon (Basagran), Benzene, Benzo[a]pyrene, Beryllium, Bromacil, Bromobenzene, Bromochloromethane, Bromomethane, Butachlor, Butanoic acid, 2,2,3,3,4,4-hexafluoro-4-(trifluoro, Butylated hydroxyanisole, Cadmium, Carbaryl, Carbofuran, Carbon tetrachloride, Chlordane, Chlorodifluoromethane, Chloroethane, Chloromethane, Chlorpyriphos, Chromium (total), cis-1,2-Dichloroethylene, cis-1,3-Dichloropropene, Cobalt, Dalapon, Di(2-ethylhexyl) adipate, Di(2-ethylhexyl) phthalate, Diazinon (Spectracide), Dicamba, Dichlorodifluoromethane, Dichloromethane (methylene chloride), Dieldrin, Dimethipin, Dimethoate, Dinoseb, Diquat, Endothall, Endrin, Ethoprop, Ethyl tert-butyl ether, Ethylbenzene, Ethylene dibromide, Germanium, Glyphosate, Heptachlor, Heptachlor epoxide, Hexachlorobenzene (HCB), Hexachlorobutadiene, Hexachlorocyclopentadiene, Hexafluoropropylene oxide dimer acid (HFPO-DA), Isopropyl ether, Isopropylbenzene, Lindane, m-Dichlorobenzene, Mercury (inorganic), Methomyl, Methoxychlor, Metolachlor, Metribuzin, Molinate, Monochlorobenzene (chlorobenzene), MTBE, n-Butylbenzene, N-ethyl perfluorooctane sulfonamido acetic acid (N, N-methyl perfluorooctanesulfonamidoacetic acid, n-Propylbenzene, Naphthalene, Nitrate, Nitrate & nitrite, Nitrite, Nonafluoro-3,6-dioxaheptanoic acid, o-Chlorotoluene, o-Dichlorobenzene, o-toluidine, Oxamyl (Vydate), Oxyflurofen, p-Chlorotoluene, p-Dichlorobenzene, p-Isopropyltoluene, Pentachlorophenol, Perchlorate, Perfluoro(2-ethoxyethane)sulfonic acid, Perfluorobutane sulfonate (PFBS), Perfluorobutanoic acid (PFBA), Perfluorodecanoic acid (PFDA), Perfluorododecanoic acid (PFDoA), Perfluoroheptane sulfonic acid (PFHpS), Perfluoroheptanoic acid (PFHPA), Perfluorohexane sulfonate (PFHXS), Perfluorohexanoic Acid (PFHxA), Perfluorononanoic acid (PFNA), Perfluorooctane sulfonate (PFOS), Perfluorooctanoic acid (PFOA), Perfluoropentane sulfonic acid (PFPeS), Perfluoropentanoic acid (PFPeA), Perfluorotetradecanoic acid (PFTA), Perfluorotridecanoic acid (PFTrDA), Perfluoroundecanoic acid (PFUnA), Permethrin, Picloram, Polychlorinated biphenyls (PCBs), Profenofos, Prometryn, Propachlor, Propanoic acid, 2,2,3,3-tetrafluoro-3-(trifluorome, Quinoline, Radium, combined (-226 & -228), sec-Butylbenzene, Silver, Simazine, Styrene, Tebuconazole, tert-Amyl methyl ether, tert-Butylbenzene, Tetrachloroethylene (perchloroethylene), Thallium, Thiobencarb, Toluene, Toxaphene, trans-1,2-Dichloroethylene, trans-1,3-Dichloropropene, Tribufos, Trichloroethylene, Trichlorofluoromethane, Trichlorotrifluoroethane, Vinyl chloride, Xylenes (total)

Find A Filter

Utility: 

Town of Discovery Bay
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Carbon Filters

FILTERS 10 contaminants exceeding guidelines (+2 others)

Can reduce the levels of many common contaminants.

pros

  • Lower upfront cost
  • Reduced maintenance

cons

  • Does not remove all contaminants

Reverse Osmosis

FILTERS 12 contaminants exceeding guidelines (+10 others)

Can reduce the levels of many common contaminants.

pros

  • Most effective

cons

  • Higher upfront cost
  • Requires more maintenance
  • Wastes water

Other Considerations

Ion Exchange

Pros: Softens hard water, Reduces some contaminants

Cons: Doesn’t remove all contaminants

Whole-House Filters

Pros: Useful for reducing radiologicals and TCE

Cons: Expensive to install and maintain, Risk of bacterial contamination

Distillation

Pros: Removes heavy metals and harmful microbes

Cons: Does not reduce most contaminants

Explore filter options for each contaminant. See which technologies are effective at reducing specific contaminants to help you make an informed decision on the best water treatment solution for your needs.

CONTAMINANTS ABOVE HEALTH GUIDELINES activated carbon reverse osmosis ion exchange
Arsenic
Bromodichloromethane
Bromoform
Chloroform
Dibromoacetic acid
Dibromochloromethane
Dichloroacetic acid
Haloacetic acids (HAA5)
Haloacetic acids (HAA9)
Total trihalomethanes (TTHMs)
Trichloroacetic acid
Uranium, combined (pCi/L)
OTHER CONTAMINANTS DETECTED activated carbon reverse osmosis ion exchange
Aluminum
Barium
Chlorate
Chromium (hexavalent)
Fluoride
Lithium
Manganese
Molybdenum
Monobromoacetic acid
Monochloroacetic acid
Selenium
Strontium
Vanadium