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Chromium and Legionella

An organization called the Environmental Working Group has released a report that says the chemical compound hexavalent chromium has been detected in water supplies across the country, including that of Tacoma Water.  

Is Tacoma’s water safe to drink?
Yes, the water provided by Tacoma Water is safe to drink.

What is chromium and why is it in the water?
Chromium is a naturally occurring element found in rocks, animals, plants, soil and volcanic dust and gases. It exists in nature in several forms including Chromium-3, an essential nutrient for the body, and Chromium-6, which can be produced by industrial processes.

What are the regulations surrounding chromium in drinking water?
Chromium-6 in drinking water is not regulated by the Environmental Protection Agency or by Washington State. However, the EPA has established a drinking water standard of 100 parts per billion (ppb) for all forms of chromium. In 2014, California established a standard for drinking water of 10 ppb and a public health goal of 0.02 ppb for Chromium-6. 

What testing has Tacoma Water completed?
Between 2013 and 2015, the EPA had many public drinking water systems across the country test for a number of unregulated chemicals, including Chromium-6. More than 60,000 samples were collected; Chromium-6 was detected in more than 75% of the samples.

 In Tacoma Water’s samples, Chromium-6 was detected at very low levels. The average of our results was approximately 0.17 ppb; our highest result was 0.31 ppb – well below California’s standard of 10 ppb. Tacoma Water’s information was provided to customers in our most recent Water Quality Report, mailed to all homes and businesses.

How does Tacoma Water protect against Chromium and other chemicals from entering the drinking water?
Most of Tacoma’s water comes from the 231-square-mile watershed that serves as a collection point for melting snow and rainfall in the uninhabited area of the Cascade Mountains between Chinook and Snoqualmie passes. Tacoma Water owns about 11% of the watershed and, through agreements with other landowners, we limit watershed access and carefully control activities, such as recreation, road maintenance and logging.  This controlled watershed offers enormous protection against industrial contamination.  The majority of Tacoma’s groundwater comes from areas protected by the South Tacoma Groundwater Protection District. This special district has added regulatory protections for storage and use of chemicals, and is administered by the Tacoma-Pierce County Health Department.

Where  can I get more information?
The EPA offers this information:



Four patients hospitalized at the University of Washington Medical Center were diagnosed with Legionella pneumonia; as of Sept. 21, two of the patients have died.

What is Legionella?
Legionella is a type of bacteria that lives naturally in fresh water. While it rarely causes illness, in certain situations, it can grow in settings like showers, faucets, cooling towers, decorative fountains and hot tubs. The associated Legionnaires’ disease is principally acquired by inhaling minute airborne droplets of water containing the bacteria. 

The challenge of Legionella in large building water supplies is not new; the bacteria and the disease it can cause was discovered after the outbreak at the 1976 American Legion Convention in Philadelphia. Compared to other bacteria, it is more resistant to standard chlorine disinfection.

How does Tacoma Water protect against Legionella in the water system?
A water system’s best defense against Legionella is robust primary disinfection, which we achieve with ozone and chlorine at the Green River Headworks. (The majority of the water we provide to our customers is from the Green River.) We also use filtration to remove organisms and fine materials that could harbor or shield bacteria. Our seasonal groundwater supplies are also all chlorinated.