Water Quality

Important Information About Your Drinking Water


Since 1991, California water utilities have been providing information on water served to its consumers.  This report is a snapshot of the tap water quality that we provided last year.  Included are details about where your water comes from, how it is tested, what is in it, and how it compares with state and federal limits.  We strive to keep you informed about the quality of your water and to provide a reliable and economic supply that meets all regulatory requirements.

How Is My Drinking Water Tested?

Your drinking water is tested regularly for unsafe levels of chemicals, radioactivity and bacteria at the source and in the distribution system. We test weekly, monthly, quarterly, annually or less often depending on the substance. State and federal laws allow us to test some substances less than once per year because their levels do not change frequently. All water quality tests are conducted by specially trained technicians in state-certified laboratories.

What Are Drinking Water Standards?

The U.S Environmental Protection Agency (USEPA) limits the amount of certain substances allowed in tap water.  In California, the Department of Public Health (Department) regulates tap water quality by enforcing limits that are at least as stringent as the USEPA’s.  Historically, California limits are more stringent than the Federal ones.
There are two types of these limits, known as standards.  Primary standards protect you from substances that could potentially affect your health.  Secondary standards regulate substances that affect the aesthetic qualities of water.  Regulations set a Maximum Contaminant Level (MCL) for each of the primary and secondary standards.  The MCL is the highest level of a substance that is allowed in your drinking water. 
Public Health Goals (PHGs) are set by the California Environmental Protection Agency.  PHGs provide more information on the quality of drinking water to customers, and are similar to their federal counterparts, Maximum Contaminant Level Goals (MCLGs).  PHGs and MCLGs are advisory levels that are nonenforceable.  Both PHGs and MCLGs are concentrations of a substance below which there are no known or expected health risks. 
How Do I Read the Water Quality Table? Although we test for over 100 substances, regulations require us to report only those found in your water.  The first column of the water quality table lists substances detected in your water.  The next columns list the average concentration and range of concentrations found in your drinking water.  Following are columns that list the MCL and PHG or MCLG, if appropriate.  The last column describes the likely sources of these substances in drinking water.
To review the quality of your drinking water, compare the highest concentration and the MCL. Check for substances greater than the MCL.  Exceedence of a primary MCL does not usually constitute an immediate health threat.  Rather, it requires testing the source water more frequently for a short duration.  If test results show that the water continues to exceed the MCL, the water must be treated to remove the substance, or the source must be removed from service.

Why Do I See So Much Coverage in the News About the Quality Of Tap Water?

The sources of drinking water (both tap water 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, including 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, which may come from a variety of sources such as agriculture, urban stormwater runoff, and residential uses;
  • Organic chemical contaminants, including synthetic and volatile organic chemicals, 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, which 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 Department prescribe regulations that limit the amount of certain contaminants in water provided by public water systems.  Department regulations also establish limits for contaminants in bottled water that must provide the same protection for public health.
All 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 USEPA’s Safe Drinking Water Hotline (1-800-426-4791).  You can also get more information on tap water by logging on to these helpful web sites:

   (USEPA’s web site)    
www.dhs.cahwnet.gov/ps/ddwem   (Department web site)

Should I Take Additional Precautions?

Some people may be more vulnerable to contaminants in drinking water than the general population.  Immunocompromised 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 from infections.  These people should seek advice about drinking water from their health care providers. The USEPA/Centers for Disease Control guidelines on appropriate means to lessen the risk of infection of Cryptosporidium and other microbial contaminants are available from the USEPA’s Safe Drinking Water Hotline (1-800-426-4791).

Source Water Assessment

MWD completed an assessment of its Colorado River and State Water Project supplies in 2002.  Colorado River supplies are considered most vulnerable to recreation, urban/storm water runoff, increasing urbanization in the watershed, and wastewater.  State Water Project supplies are considered most vulnerable to urban/storm water runoff, wildlife, agriculture, recreation and wastewater.  A copy of the assessment can be obtained by contacting MWD at (213) 217-6850.

How Can I Participate in Decisions On Water Issues That Affect Me?

The public is welcome to attend regular scheduled Board meetings.  The times and dates of the meeting are posted on our website and in front of the office.  The meetings are held at the District’s office located at 13819 E. Telegraph Road, Whittier, CA  90604. 

How Do I Contact My Water Agency If I Have Any Questions About Water Quality?

If you have specific questions about your tap water quality, please contact the Management at (562) 941-0114.
Some Helpful Water Conservation Tips:
  • Fix leaky faucets in your home – save up to 20 gallons every day for every leak stopped
  • Don’t use your toilet as an ashtray or wastebasket – save 400 to 600 gallons per month with fewer flushes
  • Adjust your sprinklers so that water lands on your lawn/garden, not the sidewalk/driveway – save 500 gallons per month