# Seattle Water Systems by My Home Water System

> Published water hardness for Seattle, WA, copied from the utility's own reports, and a way to request a written water treatment quote from one local company. Not a water utility.

## Water facts, as published
- Hardness, Cedar distribution sample, Seattle Public Utilities: 1.55 grains per gallon (Single sample, May 2026). Source: SPU Quarterly Surface Water Analysis (May 2026), non-regulatory data, https://www.seattle.gov/documents/Departments/SPU/Services/Water/Analyses/SPU_Quarterly-Surface-Water-Analysis_05-20-2026.pdf
- Hardness, Tolt distribution sample, Seattle Public Utilities: 1.53 grains per gallon (Single sample, May 2026). Source: SPU Quarterly Surface Water Analysis (May 2026), non-regulatory data, https://www.seattle.gov/documents/Departments/SPU/Services/Water/Analyses/SPU_Quarterly-Surface-Water-Analysis_05-20-2026.pdf
- USGS class, our reading of the published figures: soft. Classes: https://www.usgs.gov/water-science-school/science/hardness-water
- In 2025, 62 percent of the water came from the Cedar River and 38 percent from the Tolt.
- Seattle publishes these as informational single samples, not an annual average.
- Seattle Public Utilities lists free chlorine in both its Cedar and Tolt supplies. Its reports do not mention chloramine. Source: SPU quarterly surface water analysis, May 2026, https://www.seattle.gov/documents/Departments/SPU/Services/Water/Analyses/SPU_Quarterly-Surface-Water-Analysis_05-20-2026.pdf
- In 2025, 62 percent of Seattle water came from the Cedar River and 38 percent from the South Fork Tolt River. Source: SPU 2025 Drinking Water Quality Report, https://seattle.gov/documents/Departments/SPU/AboutUs/Reports/Water%20Quality/SPU-Drinking-Water-Quality-Report_2025.pdf
- Homes south of Green Lake usually get Cedar River water, and areas north of Green Lake usually get Tolt water, though either source can serve other areas. Source: SPU 2025 Drinking Water Quality Report, https://seattle.gov/documents/Departments/SPU/AboutUs/Reports/Water%20Quality/SPU-Drinking-Water-Quality-Report_2025.pdf
- Sources last checked: 2026-10-27

## Pages
- [Seattle water and quotes](https://seattlewatersystems.com/): the answer, the sources, common questions
- [Water data as JSON](https://seattlewatersystems.com/water.json)
- [Seattle water by source](https://seattlewatersystems.com/by-area/): where each area or utility serves, its own figures and treatment
- [Water softeners](https://www.myhomewatersystem.com/water-softeners/), [whole-home filtration](https://www.myhomewatersystem.com/whole-home-filtration/), [reverse osmosis](https://www.myhomewatersystem.com/reverse-osmosis/)
- [Hard water by city](https://www.myhomewatersystem.com/hard-water-by-city/): published hardness for every city we cover

## Status
- Not taking requests yet. No prices are published; quotes come after an assessment at the home.
- Run by My Home Water System, operated by Aidren LLC.