Seattle, Washington

Cedar and Tolt mountain water. Soft. Free chlorine, not chloramine — SPU says so on the plant pages.

Cited numbers from the utility report. Length follows the printed value against a labeled scale — not a health ranking. If the report has no number, it is not on the chart.

Hardnessabout 1.2–1.4 gpg
Free chlorinenot chloramine

On the report

Water utility: Seattle Public Utilities
Hardness: SPU quarterly surface-water analysis (samples 8/12/2025): hardness about 1.20–1.36 grains per gallon on the Cedar / Tolt columns printed there. — SPU Quarterly Surface Water Analysis, 8/12/2025
Disinfectant: Free chlorine, not chloramines. SPU Cedar and Tolt treatment pages say so in those words. — Seattle Public Utilities Cedar and Tolt treatment pages
Brine / salt to the sewer: No district prohibition found in current research. No Seattle Public Utilities sewer ban like Measure S turned up. A salt softener is usually the wrong box on this supply.

Also around here

Extra context besides the utility report and the chart above — geology, an unregulated table, or a published study. Not a second set of printed tap numbers.

MicroplasticsWHO’s 2019 review examined studies that found microplastic particles in treated tap and bottled water in many places. That is a published-occurrence finding, not a number from this city’s water-quality report, and we do not invent a particles-per-liter count for the tap.Microplastics in drinking-water — World Health Organization
PFASEPA’s Fifth Unregulated Contaminant Monitoring Rule required community systems this size to test 29 PFAS and lithium in 2023–2025. Open the UCMR 5 Data Finder for this PWS. This file does not invent a detection.Fifth Unregulated Contaminant Monitoring Rule — U.S. Environmental Protection Agency

What actually fits

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If a dealer is selling you a softener anyway

This supply is soft on the published numbers. A salt tank is usually the wrong box unless you are on a well or a different utility. Test the tap before you buy hardness equipment.

Shop water test kits

If the shower just smells like the pool

A single black whole-house carbon tank with a control head, installed in a garage and connected to copper pipe. — Whole-house carbon tank. No brine tank.

That is chlorine. A whole-house carbon filter with an NSF/ANSI 42 chlorine claim is the usual match. A softener will not take chlorine out.

Shop whole-house carbon

If you are shopping a PFAS listing for the kitchen

Under-sink reverse osmosis system with a white storage tank, filter canisters, and colored tubing in a kitchen cabinet. — Under-sink reverse osmosis: filters, tank, and a second faucet.

The under-sink RO we actually run is Cloud RO — NSF/ANSI 58, kitchen tap, not a whole-house tank. Check the exact listing if PFAS is why you are shopping. Waterdrop is a tankless option if you want that path. A certifier-listed pitcher is the cheap first step. Nobody is paying for a medical claim.

Shop Cloud RO Shop Waterdrop reverse osmosis Shop PFAS-listed pitchers

Sources

Water Quality Annual Reports — Seattle Public Utilities. Accessed 2026-08-31.
Cedar Water Treatment — Seattle Public Utilities. Accessed 2026-08-31.

Updated August 31, 2026. A city file is chemistry we can cite plus the sewer rule. No invented detections.