Sources of San Leandro, California Drinking Water

The water that the East Bay Municipal Utility District (EBMUD) provides to people in Alameda and Contra Costa County comes from the watershed of the Mokelumne River in the Sierra Foothills. EBMUD secured water rights to the river in the early 1920s and built Pardee Dam across a valley, creating Pardee Reservoir. The reservoir supplies water to more than 1.2 million people in 22 East Bay cities from San Lorenzo to Crockett, including Oakland and Berkeley. Three 6-foot-wide steel aqueducts carry the water across the Central Valley to Walnut Creek, more than 80 miles away. Gravity alone will move up to 202 million gallons a day. With all three aqueducts open and the station’s pumping plants running, EBMUD can move 325 million gallons. The energy required for all water treatment and pumping, including over the East Bay hills, is the equivalent of the energy required to power about 95 million homes. From Walnut Creek, the water goes either to a treatment plant in Orinda or to three East Bay reservoirs, where it takes on local runoff before reaching two treatment plants. Together, the reservoirs can hold enough water to supply locals for four to six months. From the treatment plants, which add chloramine and fluoride, the water flows through more than 3,944 miles of distribution pipes and 164 neighborhood reservoirs — and on to businesses and households.

Lead and Copper — Although water coming from the EBMUD water main is relatively free of these heavy metals, they can enter the water supply from pipes that connect the water main to the home, and from plumbing and faucets inside the home. Hot water systems in particular can contain elevated levels of lead and copper, and drinking water from hot water taps is inadvisable. The best way to know how much lead is in your water is to have it tested. If the lead level is more than fifteen parts per billion, it is best to filter your water. Note that lead in East Bay tap water is not common. Is San Leandro's water safe to drink?

Source: East Bay Municipal Utility District

A list of contaminants in San Leandro, California Water Supply

(Detected above health guidelines)

Chromium (hexavalent)

3rd party independent testing found that this utility exceeds health guidelines for this drinking water contaminant. The movie Erin Brockovich alerted the public to the great suffering the little town of Hinkley, California experienced due to hexavalent chromium in their drinking water. Today, Hinkley is little more than a ghost town thanks to continued water contamination, health concerns, and plummeting property values. 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. What are the risks of drinking tap water with Chromium (hexavalent)? Cancer. A 2008 study by the National Toxicology Program, part of the National Institutes of Health, found that chromium-6 in drinking water caused cancer in laboratory rats and mice. That study and other research led scientists at the California Office of Environmental Health Hazard Assessment to conclude that chromium-6 can cause cancer in people. Find out more about this contaminant and how to remove it here.

Total Trihalomethanes (TTHMs)

3rd party independent testing found that this utility exceeds health guidelines for this drinking water contaminant. Total Trihalomethanes (TTHMs) are the result of a reaction between the chlorine used for disinfecting tap water and natural organic matter in the water. At elevated levels, TTHMs have been associated with negative health effects such as cancer and adverse reproductive outcomes. Now a study by government and academic researchers adds to previous evidence that dermal absorption and inhalation of TTHMs associated with everyday tap water use can result in significantly higher blood TTHM concentrations than simply drinking the water does. What are the risks of drinking tap water with Total Trihalomethanes (TTHMs)? Cancer. Studies from around the world including the United States & Europe have found that drinking tap water that carries Total Trihalomethanes increases the risk of developing cancer. In animal studies, all trihalomethanes cause liver, kidney and intestinal tumors. Find out more about this contaminant and how to remove it here.


There is a drinking water standard of 4 ppm for fluoride but there is no health guideline for this contaminant and much is not known about the effects of fluoride long term on the human body. This water utility did not exceed the drinking water standard for fluoride but fluoride was found in their water. Fluoride occurs naturally in surface and groundwater and is also added to drinking water by many water systems. The fluoride that is added to water is not the naturally occurring kind, the main chemicals used to fluoridate drinking water are known as “silicofluorides” (i.e., hydrofluorosilicic acid and sodium fluorosilicate). Silicofluorides are not pharmaceutical-grade fluoride products; they are unprocessed industrial by-products of the phosphate fertilizer industry (Gross!). Since these silicofluorides undergo no purification procedures, they can contain elevated levels of arsenic — more so than any other water treatment chemical. In addition, recent research suggests that the addition of silicofluorides to water is a risk factor for elevated lead exposure, particularly among residents who live in homes with old pipes. What are the risks of drinking tap water with Fluoride? Unknown. A growing body of evidence reasonably indicates that fluoridated water, in addition to other sources of daily fluoride exposure, can cause or contribute to a range of serious effects, including neurological issues, arthritis, damage to the developing brain, reduced thyroid function, and possibly osteosarcoma (bone cancer) in adolescent males. Animal studies indicate a moderate level of evidence that support adverse effects on learning and memory in animals exposed to fluoride in the diet or drinking water. Find out more about this contaminant and how to remove it here.

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April Jones
Hiker, blogger, clean living enthusiast, water quality expert