California Water Service - San Mateo Drinking Water Quality Report

Water Test Results (Published 2016)

Lead was not detected in the water supply.

Before examining the data, there are two important things to know about investigating lead levels in water. The first is that these levels are measured in parts-per-billion or PPB. For example, three parts lead in one billion parts water equals three PPB. The second thing to know is that no amount of lead in drinking water is considered safe by either the Environmental Protection Agency (EPA) or the Centers for Disease Control (CDC).

Exposure to even low levels of lead is particularly harmful to children, infants, and fetuses and has been linked to nervous-system damage, learning disabilities, shorter stature, impaired hearing, and impaired formation and function of blood cells. So, the ideal PPB level for everyone is zero. In fact, that's the maximum contaminant level goal for lead in water set by the EPA. However, some homes, especially older ones, have pipes and pipe fixtures made of lead, which means tiny amounts of lead can leach from the pipes into the water even if the local water supply contains absolutely no lead at all.

Because of this, the EPA has created an action level for lead of 15 PPB, which is triggered if at least 10% of an area's homes are tested and found to have lead levels of 15 PPB or higher. The EPA then alerts that community's water consumers and requires additional testing. Health experts, however, consider just five PPB to be a cause for concern. The main point here is that the closer the PPB is to zero, the better.

Finally, while this report gives a helpful snapshot of the lead level, the best way to determine the lead level of the drinking water in your home is to test it yourself or send a sample to an accredited lab to be tested. To learn more about testing and treating lead in water, read these articles:

• “Six Ways to Detect Lead in Your Drinking Water”
• “How to Test for Lead in Your Water and What to Do If There's Too Much”
• “Three Tried and Tested Ways to Remove Lead from Water”
• “Basic Information about Lead in Water”

Also, to discover more about water quality, water contaminants, water filters, water dispensers, and other general water-related content, visit WaterZen.com's Water Resources Page.

*Based on public health goals (MCLG) and the maximum allowed by law (MCL) set by the EPA.

Water Test Results (Published 2016)

Copper was not detected in the water supply.

When it comes to public health, copper plays a dual role: one positive and one negative. On the plus side, copper is a mineral that's essential to human health, found naturally in some foods, and added as a supplement to others. The recommended daily allowance for adults listed by the National Institute for Health is 900 micrograms (mcg) per day. (Copper in water is measured in mcg per liter.)

However, while some copper intake enhances health, too much of it for prolonged periods of time can damage the liver and kidneys, and cause gastrointestinal issues such as abdominal pain, cramps, nausea, diarrhea, and vomiting. This copper toxicity has been reported in people whose drinking water contained high levels of copper that had leached off pipes and plumbing fixtures in their homes or in their water distribution system.

To learn more about copper and other contaminants in drinking water, read these articles:

• “Everything You Need to Know about Copper in Drinking Water”
• "A Guide to the Most Common Types of Drinking Contaminants”

Also, to discover more about water quality, water filters, water dispensers, and other general water-related content, visit WaterZen.com's Water Resources Page.

*Based on public health goals (MCLG) and the maximum allowed by law (MCL) set by the EPA.