Water Quality FAQ

Like other public water agencies in Orange County, YLWD depends on two sources of water. Approximately 70% of our total domestic water supply is local groundwater pumped from wells.

The remainder is imported water purchased from the Metropolitan Water District of Southern California (MWD). MWD imports water from the Colorado River via the Colorado River Aqueduct and from Northern California via the California Aqueduct, also known as the State Water Project.

Imported water is treated at MWD’s Diemer Water Treatment Plant, located on Valley View and Diemer Road in Yorba Linda, and disinfected using chloramines, a combination of chlorine and ammonia. YLWD uses chlorine to disinfect well water as it enters the distribution system. Because your water sources vary or maybe a blend of these two supplies, you may notice a difference in the taste or hardness (mineral content) of the water at different times of the year. None of these factors affects the quality and safety of your water.

Having multiple sources of water is beneficial for YLWD customers. Local groundwater is both higher in quality and lower in cost than imported water, which must travel hundreds of miles through aqueduct systems. Having more than one source also improves the overall reliability of our water supply.

Our water comes from the Colorado River, Northern California, and local wells, with the mix varying throughout the year. The well water that YLWD supplies is pumped from hundreds of feet below the ground. That pumping process can sometimes result in aeration or the mixing of air with water. Aeration creates small bubbles in the water that are harmless but may give the water a cloudy appearance. This mixing of air into the water is also very common with the Metropolitan Water District aqueducts that typically run very full during the summer months.

Tip: If your water looks cloudy, pour some water into a clear glass and let it sit for a minute. As the air bubbles leave the water, the cloudiness will generally disappear. If the cloudiness does not clear, call YLWD at (714) 701-3000.

Water hardness refers to the mineral content in the water and is commonly expressed in “grains per gallon” of hardness. Generally, water with 13 grains or more is considered “hard.” Water imported from the Colorado River and Northern California averages 18 grains of hardness while YLWD’s well water averages 20 grains of hardness.

Although the hardness of the water does not affect its safety, the higher mineral content can cause white spots on glasses in the dishwasher. YLWD receives water from the Colorado River, Northern California, and local wells. The water supply can change throughout the year. Because our water is blended from a variety of sources, you may notice spotting on glassware. YLWD customers who live on the West side of the District tend to receive more groundwater year-round and may have hard water.

If you are concerned with hard water and spotting, it is best to read the owner’s manual for your dishwasher and follow the manufacturer’s recommendations regarding settings for hard water. Some other tips that may help reduce spotting include using more cold water instead of hot, varying the brand and type of rinse agent and detergent, and adding white vinegar to the rinse cycle of the dishwasher.

Fluoride has been added to the United States drinking water supplies since 1945. Of the 50 largest cities in the country, 43 add fluoride to their drinking water. In late 1995, the State of California passed a law (AB 733) requiring the California Department of Public Health to adopt regulations that require the fluoridation of the water of any public water system with at least 10,000 service connections when the state provided funding. While this funding was never made available to YLWD, in December of 2007, the regional wholesale water supplier, Metropolitan Water District, joined a majority of the nation’s public water suppliers in adding fluoride to drinking water in order to prevent tooth decay. In line with recommendations from the California Department of Public Health and the U.S. Center for Disease Control and Prevention, MWD adjusted the natural fluoride level in imported treated water from the Colorado River and State Project water to the optimal range for dental health of 0.7 to 1.3 parts per million.

While there is naturally occurring fluoride in our water, YLWD does not add fluoride to its drinking water supplies. The fluoride content in our groundwater averages 0.5 parts per million, while the level in water imported from the Colorado River and Northern California averages 0.8 parts per million.

Since YLWD’s water supply is made up of approximately 30% water from MWD and 70% groundwater, our water has fluoride levels in the range of 0.5 to 0.8 parts per million (milligrams per liter) depending on the source of water served in your area at any given time. Because YLWD’s wells already contain a level of fluoride close to the recommended amount, YLWD does not add additional fluoride to our water.

If you are concerned about your children’s requirement for fluoride, we suggest you provide your dentist or pediatrician with the fluoride content figures above so a supplement can be prescribed if your health care professional feels it is warranted.

Questions about MWD’s fluoridation policy may be directed to Edgar Dymally at (213) 217-5709.

Regular filters and boiling will not remove fluoride, but fluoride can be removed using a reverse osmosis system.

Sodium is a safe and natural ion found in all water. The average sodium level in MWD imported water is 95 parts per million. The average level in groundwater is 89 parts per million. Neither the state nor the federal government has set a maximum contaminant level (MCL) for sodium. Customers who have concerns about sodium intake should discuss these figures with their physician and follow their recommendation.

Chromium is an element found in nature. It is commonly used in manufacturing activities such as steel hardening, aerospace manufacturing, the making of paint pigments, and electroplating. When chromium is used in industrial processes, it is often converted to chromium 6.

Chromium may be present in water as chromium 3 and chromium 6. Chromium 3 is an essential nutrient at trace concentrations. Chromium 6 can be present in many forms, some of which are carcinogenic when inhaled at high concentrations. Tests conducted on YLWD’s water have identified chromium 6 in extremely low concentrations in all our water wells.

Current regulatory standards assure safe levels of total chromium, the combination of chromium 3 and chromium 6—in drinking water to protect against any possible inhalation hazard. In fact, as an added measure of safety, the state has established a very stringent health protection level for chromium in drinking water even before all the necessary health studies have been completed to set a formal regulation.