Seattle Water Quality Facts and Drinking Water Problems

A small baby enjoys his bubble bath in the sink as his mother washes his hair with bubbly water.

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Before water reaches your tap, it is sourced from a complex system of surface water and groundwater from around Washington that includes lakes, rivers, streams, reservoirs, wells, and more. After water is pumped from these sources, it is purified, cleaned, and tested at a water treatment plant before being distributed throughout the state.

While the quality of Washington’s water varies significantly depending on the region, residents of the Evergreen State often report their water being hard, which contributes to cloudy dishes and glassware, limescale or white scale buildup, and soap scum residue in bathroom areas.

Common Water Issues in Seattle

Seattle sources its drinking water from two large regional watersheds – the Cedar and Tolt. Roughly 70% of the city’s drinking water comes from the Cedar River Watershed, while the Tolt River Watershed supplies the other 30%. The water is typically treated at either the Cedar Water Treatment Facility or the Tolt Water Treatment Facility before being distributed throughout the city to homes and businesses in the Seattle metro area.

The most common water quality issues in the Seattle area include:

Lime or White Scale Buildup

Limescale is the hard, off-white deposit that creates buildup on many household items as a result of using hard water around the house. Some examples of this include:

Pesky sediment and scum buildup on bathroom and kitchen appliances
Under-performing appliances that result in added household costs
Off-white buildup that causes faucets and showerheads to clog
Difficult-to-clean surfaces

Soap Scum and Sediment

As a result of hard water, soap scum can make even simple cleaning projects a pain. Evidence of soap scum around the house includes::

Buildup on household appliances and faucets
Cloudy dishes and glassware
Uncomfortable film on skin and hair

Spots on Glasses

Whether you wash your dishes by hand at the tap or you let your dishwasher do the work for you, dishes that are washed and rinsed with hard water can appear spotty and streaky after water dries.