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Is Seattle Tap Water Safe to Drink?

Scott Winfield
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by Scott Winfield

If you live in Seattle, you may find yourself wondering whether the water from your tap is drinkable. How high is the quality? Is it better or worse than other cities in the United States?

It’s crucial to know with certainty that your tap water is safe to avoid getting sick. Let’s take a closer look at Seattle’s tap water to determine the facts.  

Seattle Water Quality Report: What is in the Water?

Is Seattle tap water safe to drink? The answer is yes, according to the EPA. The tap water is filtered and treated, and in many cases, is of higher quality than other cities in the United States.

But what is inside the water supply before the decontamination?

Microbial contaminants exist in Seattle’s drinking water. Bacterial particles and viruses can creep into the water supply and, if left untreated, can make those who drink it unwell. A specific example is Legionella.

This bacteria can lead to some of the more horrific cases of pneumonia. Unfortunately, it grows in freshwater lakes and the surrounding soil.

Despite the dangers of this bacteria and how easily it can appear in water supplies, Seattle has some of the lowest rates of Legionnaires’ disease.

According to Seattle Public Utilities, daily water quality checks deem Seattle’s water safe.

Is The Water Hard or Soft?

Seattle water is considered very soft. Soft means that there are very few calcium and magnesium minerals in the water supply. It’s rare to come across soft water, as only 15% of the United States water is considered soft.

Seattle’s water supply is classified at less than 17 parts per million, meaning the city is in the soft water zone, which contributes to not only the safety of consuming it but the taste of the water.

Where Seattle Gets its Water From

Seattle’s primary water source is the Cedar River Watershed, a massive part of the Cedar River Basin. This watershed provides around 70% of Seattle’s water supply. The pipes receive their water from the Lower Cedar River where water quality tests are performed as well.

This means that Seattle’s water is doubly filtered: first in the Lower Cedar River, then in the city itself.

 Cedar River
Cedar River, Seattle

A secondary source for Seattle’s tap water is the Tolt River Watershed. It’s a lesser known river that supplies around 30% of water supply to Seattle’s population.

The Tolt River Watershed is also treated and monitored for quality, so it’s safe to say both sources are treated twice before the water is flowing through your sink or shower.

You may feel more comfortable with this information, but let’s also look at how the water is treated to bring even more peace of mind.

How Tap Water Is Treated in Seattle

With so many potential bacterial contaminants in every water supply, the city has to treat the water before it can be safely consumed. Seattle’s tap water has quality-checked sources and water quality control in their pipelines.

Testing Water from a Faucet

Seattle’s water supply is chlorinated twice for contaminants and treated for inactive microbial bacteria. The land around the watersheds provided a protective barrier, and so does the ultra-violet light and ozone that offers an even deeper cleanse to the water.

Within a year, there are more than 20,000 tested samples, water quality checks each day, and the water sources are filtered before the water even arrives at Seattle’s pipelines.

These allow for safe, tasty water that won’t put you at risk of illness or diseases.

As previously stated, Legionella is one of the more dangerous illnesses potentially transferred through Seattle’s tap water. The explanation for why there are so few reported cases of Seattle residents with Legionnaires’ disease is because of Seattle’s filtration system and chlorine treatment.

The chlorine treatment kill bacteria but never exceed unsafe levels. Excess chlorine in water can cause health issues, so its usage is regulated and tested to be safe.

Do They Have the Cleanest Tap Water?

Seattle drinking water is considered one of the cleanest in the country. It’s not the highest on the list, but it is up there with its soft and high-quality water supply from two water quality-controlled river watersheds. 

While unsafe water conditions can occur, Seattle is constantly vigilant to make sure that your water is clean, soft, and safe.


Seattle has one of the safest water supplies in the country with its filtration, chlorine treatment, and constant water quality vigilance.

If you live in Seattle, your water safety and taste quality are both high. In case of the scenario that your water is cloudy or tastes unusual, stop drinking and visit the Seattle Public Utilities for a quality report.

Bottom line: Seattle tap water is safe to drink.

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Scott Winfield
Scott Winfield
My name is Scott Winfield and researching and writing about water filters and other strategies to purify water has become my full time passion in recent years. I'm glad that you found our site and you can look forward to authoritative and well researched content here to help you get the best in water.
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