Why is my water yellow?
Yellow water is caused by seasonally elevated levels of the naturally occurring minerals iron and manganese; they are found in the Green River water supply. Discolored water is most often described as "yellow water," but it  can also appear slightly green, red or brown. Customers most often notice yellow water against white backgrounds like bathtubs, sinks, toilets and hot tubs.

Is my water safe to drink?

Yes. Tacoma Water meets all health-based drinking water standards. We monitor, disinfect and routinely test for more than 150 different chemicals in our drinking water annually. We also test nearly 200 coliform bacteria samples from throughout our system monthly.

What seasonal conditions cause yellow water?

In the Eagle Gorge Reservoir behind Howard Hanson Dam, water nearest the surface warms during the summer, while colder water sinks to the bottom. Eventually, the reservoir becomes separated into layers by temperature. As oxygen is used up in the deeper water, it cannot be easily replenished and depletes. Low oxygen levels can cause iron and manganese in the reservoir's sediments to dissolve into the water supply. When the iron and manganese react with chlorine and ozone at the water treatment plant, the minerals become even more visible in the water. Chlorine and ozone are required to help ensure the safety of the drinking water.

Can Tacoma Water remove iron and manganese in water?

Not currently. Few effective treatment alternatives exist. Chemicals intended to keep these minerals invisible are available, but they are not feasible in our larger water system.

What is Tacoma Water currently doing to improve yellow water?

Tacoma Water helps minimize yellow water by modifying operations where possible. We regularly collect and evaluate water quality information to better understand yellow water.

Who can I contact with additional questions?

For more information, please call our Water Quality group at (253) 502-8207.