{
  "city": "Seattle",
  "state": "WA",
  "slug": "seattle",
  "hardness_facts": [
    {
      "utility": "Seattle Public Utilities",
      "measure": "Hardness, Cedar distribution sample",
      "value_as_published": "1.55 grains per gallon",
      "period": "Single sample, May 2026",
      "source_title": "SPU Quarterly Surface Water Analysis (May 2026), non-regulatory data",
      "source_url": "https://www.seattle.gov/documents/Departments/SPU/Services/Water/Analyses/SPU_Quarterly-Surface-Water-Analysis_05-20-2026.pdf"
    },
    {
      "utility": "Seattle Public Utilities",
      "measure": "Hardness, Tolt distribution sample",
      "value_as_published": "1.53 grains per gallon",
      "period": "Single sample, May 2026",
      "source_title": "SPU Quarterly Surface Water Analysis (May 2026), non-regulatory data",
      "source_url": "https://www.seattle.gov/documents/Departments/SPU/Services/Water/Analyses/SPU_Quarterly-Surface-Water-Analysis_05-20-2026.pdf"
    }
  ],
  "published_span_mg_per_l": [
    26,
    27
  ],
  "span_converted_from_grains": true,
  "usgs_class": "soft",
  "usgs_class_source": "https://www.usgs.gov/water-science-school/science/hardness-water",
  "notes": [
    "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."
  ],
  "local_details": {
    "disinfectant": {
      "text": "Seattle Public Utilities lists free chlorine in both its Cedar and Tolt supplies. Its reports do not mention chloramine.",
      "kind": "chlorine",
      "source_title": "SPU quarterly surface water analysis, May 2026",
      "source_url": "https://www.seattle.gov/documents/Departments/SPU/Services/Water/Analyses/SPU_Quarterly-Surface-Water-Analysis_05-20-2026.pdf",
      "evidence_ids": [
        "SEATTL-L-01"
      ]
    },
    "source_water": {
      "text": "In 2025, 62 percent of Seattle water came from the Cedar River and 38 percent from the South Fork Tolt River.",
      "source_title": "SPU 2025 Drinking Water Quality Report",
      "source_url": "https://seattle.gov/documents/Departments/SPU/AboutUs/Reports/Water%20Quality/SPU-Drinking-Water-Quality-Report_2025.pdf",
      "evidence_ids": [
        "SEATTL-L-02"
      ]
    },
    "by_area": {
      "text": "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_title": "SPU 2025 Drinking Water Quality Report",
      "source_url": "https://seattle.gov/documents/Departments/SPU/AboutUs/Reports/Water%20Quality/SPU-Drinking-Water-Quality-Report_2025.pdf",
      "evidence_ids": [
        "SEATTL-L-03"
      ]
    }
  },
  "sources_checked_on": "2026-10-27",
  "site": "https://seattlewatersystems.com/",
  "brand": "Seattle Water Systems by My Home Water System",
  "taking_requests": false
}