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Is Seattle Tap Water Safe To Drink?



In many ways, Seattle is the heart of the Pacific Northwest. Called “the Emerald City” for its lush greenery and thousands of acres of parkland, much of the area’s character is shaped by its proximity to the water — particularly Puget Sound and the nearby Pacific Ocean. Of course, this doesn’t just make Seattle a favorite location for whale-watching; it also means the city has a unique story when it comes to tap water.

So, is Seattle tap water safe to drink? Here’s what to know — from the city’s water source and treatment processes to home filtration recommendations.

Tap Water Quality in Seattle

The first thing to know about the tap water supply in most parts of North America is that it’s generally safe to drink. That’s because guidelines such as the U.S. National Primary Drinking Water Regulations provide “legally enforceable primary standards and treatment techniques” for the national water system. Canada has similar regulations outlined in the Guidelines for Canadian Drinking Water Quality.

At a local level, most areas also work to protect public health through a variety of treatment systems and solutions. For example, you’ve likely heard that drinking tap water is safe because your city uses chlorine to decontaminate it — but there are a lot of other steps, including multiple kinds of filtration, that help limit contaminant content.* To ensure these processes are safe, drinking water regulations in the U.S. also have guidelines for disinfection byproducts — substances formed when disinfectants interact with natural organic materials in water.

Seattle’s Safe Drinking Water

Of course, the Emerald City is no exception to these regulations. The Seattle water utility provides water to 1.5 million people per day through a system of 13 reservoirs, 14 storage tanks, 600+ water quality workers and a “mission control” center to ensure the water supply is always taken care of. The utility also has two state-of-the-art treatment facilities that treat millions of gallons of water daily.

The story of Seattle’s tap water begins at two key sources: the Cedar River and South Fork Tolt River watersheds. The former is owned by the City of Seattle and covers more than 90,000 acres — many of which you can explore via recreation areas and trails. It’s also protected from housing, agriculture and industrial work, making it one of only four major U.S. water systems that do not require filtration as part of treatment. (Many Seattle locals still choose home filtration solutions for a variety of reasons — more on that later.) The Tolt River watershed is smaller, providing only about 30% of the city’s drinking water, and is located in the Cascade Mountains.

As part of this natural, interconnected water system, the city uses restricted-access lakes to store water before treatment. That means environmental conditions, such as algae growth and temperature changes, can sometimes impact water quality, creating an unpleasant water taste or odor. Fortunately, experts from the Seattle water utility carefully study these variables and monitor the lakes and pump stations.

From there, Seattle’s tap water may go through various processes depending on the water source and treatment facility:

  • Ozone generation and injection: Ozone acts as a disinfectant and helps remove any odd water taste or odor caused by environmental conditions. By the time the water reaches the next step, the ozone decays and is neutralized.
  • Ultraviolet light (UV) disinfection: Next, the treatment center uses high-intensity light to inactivate certain pathogens, including Cryptosporidium, which is resistant to chlorine.
  • pH adjustment: Seattle water also undergoes “corrosion control,” a process that uses lime addition to raise the water’s pH to about 8.2. This helps make it less corrosive to lead and copper plumbing.
  • Fluoridation: Based on public votes, all of Seattle’s water sources have added fluoride for dental health.
  • Chlorination: Seattle uses free chlorine, not chloramines, as a disinfectant at the treatment plant and beyond. People who live closer to the plant may notice a stronger chlorine smell in tap water because the disinfectant has more time to dissipate the further it travels.

But that’s not all. The city also uses its Water Quality Laboratory to collect and analyze over 20,000 water samples per year. Experts are hard at work every day ensuring that Seattle’s water is reliable. On top of all this, the Environmental Protection Agency (EPA) requires cities to provide Water Quality Annual Reports so consumers can learn more about how tap water is treated and managed.

What About Hard Water in Seattle?

While not a drinking water concern, hard water can still cause problems for your home, budget, hair and skin. Water hardness varies depending on the source, geographic location and more, so any home in the country might have these issues — Seattle included.

The good news is that a water softener can trap and flush out the minerals that cause hard water, particularly calcium and magnesium. You’re left with soft water that doesn’t cause mineral buildup, spotty dishes, dry hair and skin, reduced appliance performance or any other frustrations. Plus, water softeners can complement other at-home treatment solutions — which, as you’ll see, might be an important consideration for Seattle locals.

Solutions for Seattle Tap Water

Although drinking tap water is generally safe, you may still want a bit of extra filtration. Why? Even the best water treatment facility can’t control what happens when water passes through your home plumbing, and other variables — such as your preferences for taste, odor and appearance — are always at play. Additionally, not all potential water issues are included in existing regulations.

Here are a few water quality issues Seattleites should be aware of:

  • Lead: There’s no detectable lead in Seattle’s source water, but city tests have identified lead in some home tap samples. This is often due to home plumbing system.
  • Copper: Seattle homes may also have copper piping, which can cause this metallic element to end up in your drinking glass.
  • Legionella: The City of Seattle notes that this bacteria, responsible for a serious type of pneumonia, sometimes grows in local building water systems.
  • Cloudiness: If you notice discoloration, foaming or gray sediment in your tap water, you may need to report an issue.
  • Tastes and odors: A variety of factors can impact Seattle water aesthetics — even the chlorine used to protect the system.

If you notice one of these issues — or any change at all in your water quality — it’s smart to have a professional water test. In about 30 minutes, your local water expert will be able to tell you your water’s hardness and pH levels, note potential contaminants and recommend personalized solutions.

Often, this will include a drinking water filtration system. Comprehensive, reliable and long-lasting, these systems help address many of the issues most common in Seattle tap water. (Remember that, while water softeners and filtration systems are separate solutions, they can be complementary parts of a full treatment approach.)

Take Control of Your Water in Seattle

Whether you’ve been in Seattle long enough to know Pike Place Market like the back of your hand or are still a little awed by the fact that you just moved so close to the Space Needle, the truth is that local water will always be a huge part of your life in Washington. Fortunately, you can always take control.

Schedule your free, in-home water test and consultation to learn more about your Seattle water and how to improve it.

*Contaminants may not be present in your water.

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