About TPU > Services > Water > About Tacoma Water > Water Quality > Water Quality FAQ

Water Quality FAQ

Why is my water yellow?

Yellow water is caused by high levels of the minerals iron and manganese, both of which occur naturally in the Green River. It is most noticeable during the summer months. Discolored water is most often described as “yellow water,” but it can also appear slightly green, red or brown. Yellow water is most often noticeable when viewed against white backgrounds such as 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. As the reservoir separates into layers by temperature, oxygen is used up in the deeper water where it cannot be easily replenished. As it depletes, these low oxygen levels can cause iron and manganese in the reservoir’s sediments to dissolve into the water supply that goes to the water treatment plant.

Then, when the iron and manganese react with chlorine and ozone that is added 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?

While our filtration system does reduce the levels of iron and manganese in the water supply it does not completely remove them. Treatment to completely remove these minerals is available, but it is not feasible in very large water systems such as ours.

What is Tacoma Water currently doing to improve yellow water?

We help minimize yellow water by modifying operations where possible. We also 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.

Cross Connection FAQ

How often should I test my backflow prevention assembly?

To protect your drinking water from potential contamination, you should test it every year.

Why is this testing necessary?

The only way to ensure your backflow prevention assemblies are working properly — and keeping you and your family safe — is to have them tested by a certified backflow assembly tester (BAT). For this reason, the Uniform Plumbing Code (Section 603) and the Washington Administrative Code (Section 246-290-490) require annual testing of installed backflow prevention assemblies.

Who can test backflow prevention assemblies?

All backflow prevention assemblies must be tested by a state-certified BAT. For your convenience, Tacoma Water has compiled a list of testers who have provided us with a copy of their certifications. This list provides contact information for these testers, but you are not required to use a BAT from our list. You can find additional testers on the Washington Certification Services website.

If you select a BAT not on our list, please make sure that the tester provides us with copies of their current state certification and test equipment calibration certificates. We will not accept test reports from testers who have not provided that information.

What is the Authorized Tester Program and what are the benefits of participating?

The Authorized Tester Program allows us to send your annual test reminder directly to a BAT of your choice. It also lets us discuss your test results directly with the tester. This frees you from having to send test results to us since we will request them from the BAT. There is no cost for using the program.

I have my backflow assembly tested every year as required, but my neighbor says he has never heard of the testing requirement. Why is that?

The most likely reason is that we were not informed about the installation, so could not send them test due notices. Sometimes customers make modifications to their water system without the required permits. Getting a permit ensures your work is inspected and installed to code. Most importantly, it ensures that you, your family and, if applicable, your customers are protected.

Your neighbor may also have installed a non-testable device. There are specific installation requirements that must be met for non-testable devices that make them impractical for many customers to use.

Q: I no longer using my irrigation system . Do I still need to test the backflow assembly?
Yes. To help protect you from contamination, as long as the irrigation system is physically connected to the water system, your backflow prevention assembly must be tested annually. We will suspend the testing requirement if you provide a physical disconnect between the irrigation system and the public water supply by removing the backflow prevention assembly and capping the water supply line. After you cap the line, you must contact our Water Quality department at (253) 502-8207 to arrange for a verification inspection. You will then no longer have to test your system.

What happens if I choose not to test my backflow prevention assembly?

We hope you understand that testing is for your protection, but if choose not to test your backflow prevention assemblies as required, we may take the following enforcement action:

Assess a $100 fee for each assembly not tested and add it to your bill. Additional fees of $100 will be added until testing is satisfactorily completed.
Install a reduced pressure backflow assembly at your water meter at your expense.
Terminate your water service.

Who can I call if I have questions about backflow prevention?

Please contact us at 253-502-8207 or backflow@cityoftacoma.org.

Cross Connection Terms

Authority having jurisdiction – This refers to the official, board, department or agency authorized to administer and enforce the provisions of the Uniform Plumbing Code. In Tacoma, the Public Works Department’s Building and Land Use Services Office is the Authority Having Jurisdiction but Tacoma Water is responsible for cross connections.

Authorized tester – The backflow assembly tester (BAT) designated by you as the customer to perform the annual backflow assembly testing. Under our Authorized Tester Program, Tacoma Water automatically sends the test due notices to the chosen tester on your behalf.

Backflow – The unwanted reversal of the flow of water or other substances through a cross connection into the public water system or the consumer’s water system.

Backflow assembly tester (BAT) – A person certified by the state of Washington to test backflow assemblies. See our current list of testers who have provided us with a copy of their certifications.

Cross connection – Any actual or potential physical connection between a public water system or the consumer’s water system and any source of nonpotable liquid, solid or gas that could contaminate the potable (drinkable) water supply by backflow.

Double check valve assembly – A testable assembly approved for installation by the State of Washington Department of Health that consists of two independently loaded check valves and two resilient seated shut off valves.

Double check detector assembly – A testable assembly approved for installation by the State of Washington Department of Health that consists of two approved double check valve assemblies arranged in parallel. The bypass assembly is equipped with a meter to detect leakage or water use.

High health hazard – A cross connection that could impair the quality of water and create a public health hazard through poisoning or spread of disease.

Low health hazard – A cross connection that could cause an impairment of the quality of water to a degree that does not create a hazard to public health but does negatively affect the water’s appearance, taste and odor.

Pressure vacuum breaker assembly – A testable assembly consisting of an internally loaded check valve, an independently operating air inlet valve and two resilient seated shut-off valves.

Reduced pressure backflow assembly – A testable assembly approved for installation by the State of Washington Department of Health that consists of two independently loaded check valves, a spring-loaded differential pressure relief valve and two resilient seated shut-off valves.

Brochures

The following brochures contain general information about cross connection control issues. For specific requirements please contact us at 253-502-8207 or backflow@cityoftacoma.org.

Cross Connection Resources

Chromium and Legionella FAQ

Why do you check for chromium in the water?

In 2016, the Environmental Working Group released a report confirming that the chemical compound hexavalent chromium had 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 regarding 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, and Chromium-6 was detected in more than 75% of the samples.

In our 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.

How you protect against Chromium and other chemicals from entering the drinking water?

Most of Tacoma’s water comes from the 231-square-mile watershed 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 about chromium?

The EPA offers the following information:

Legionella

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 showers, faucets, cooling towers, decorative fountains and hot tubs. The Legionnaires’ disease it can cause is usually acquired by inhaling minute airborne droplets of water containing the bacteria. Compared to other bacteria, it is more resistant to standard chlorine disinfection.

How do you protect against Legionella in the water system?

We treat for Legionella by disinfecting the water with ozone and chlorine at our filtration facility. There we also use filtration to remove organisms and sediment that could harbor or shield bacteria. Our seasonal groundwater supplies are also all chlorinated.