Most Washington City Water Is Soft, and That's the Truth

Washington is one of the clearer exceptions to America's hard-water belt. Seattle's supply, fed by the Tolt and Cedar watersheds, runs around 1.2 grains per gallon, which is very soft. Thank the geology and the weather: volcanic rock and heavy rainfall produce surface water that carries very little dissolved calcium or magnesium. For a large share of Washington households on treated surface water, hard-water scale simply is not a meaningful threat to the water heater.

Where Scale Actually Becomes an Issue

The picture shifts when you move off municipal surface water and onto a well. Washington's rural and private wells commonly test near 6 grains per gallon, moderately hard, because groundwater has time to pick up mineral that rainwater and reservoirs never do. On those supplies a water heater can accumulate a sediment layer in the tank or scale on a tankless exchanger, and the usual penalty applies: about a quarter-inch of scale can cost 25 to 40 percent of the unit's efficiency. That is a real concern, but it is a well concern, not a Seattle-tap concern.

Know Your Source Before You Spend

This is the honest heart of the Washington story: do not buy scale protection you may not need. If you are on Seattle-area or similar soft surface water, your heater is probably fine as is. If you are on a private well, test it, both for hardness and for iron, and then decide.

• Seattle and Tolt/Cedar surface supplies: ~1.2 gpg, very soft
• Rural and private wells: around 6 gpg, moderately hard
• Iron: possible on wells, so test for it

What These Units Are, Plainly

Our salt-free units are conditioners, not softeners. They do not remove hardness and they do not remove iron. For a Washington well testing moderately hard, a conditioner can reduce the new scale that bonds to hot surfaces, helping keep a clean heater efficient. For soft city water, you likely don't need one, and we will say so.

Here's the right-sized salt-free scale protection for your Washington water heater:

Salt-free conditioners reduce and help prevent new water-heater scale; they are not softeners and do not remove existing hardness. Free U.S. shipping. See our hard water guide.