{
  "city": "St. Louis",
  "state": "MO",
  "slug": "st-louis",
  "hardness_facts": [
    {
      "utility": "City of St. Louis Water Division",
      "measure": "Total hardness",
      "value_as_published": "Average 129 ppm, range 80-206 ppm",
      "period": "Calendar year 2025",
      "source_title": "ST. LOUIS CITY WATER - A HISTORY OF EXCELLENCE (2025 Consumer Confidence Report)",
      "source_url": "https://www.stlwater.com/ccr.pdf"
    }
  ],
  "published_span_mg_per_l": [
    80,
    206
  ],
  "span_converted_from_grains": false,
  "usgs_class": "moderately hard to very hard",
  "usgs_class_source": "https://www.usgs.gov/water-science-school/science/hardness-water",
  "notes": [],
  "local_details": {
    "disinfectant": {
      "text": "The St. Louis report lists chloramine as a treatment additive, at 1.67 to 3.46 ppm in 2025.",
      "kind": "chloramine",
      "source_title": "St. Louis Water Division Consumer Confidence Report",
      "source_url": "https://www.stlwater.com/ccr.pdf",
      "evidence_ids": [
        "STLOUI-L-01"
      ]
    },
    "source_water": {
      "text": "The Chain of Rocks plant draws from the Mississippi River and the Howard Bend plant from the Missouri River.",
      "source_title": "St. Louis Water Division Consumer Confidence Report",
      "source_url": "https://www.stlwater.com/ccr.pdf",
      "evidence_ids": [
        "STLOUI-L-02"
      ]
    },
    "softening": {
      "text": "Yes. The city report lists precipitative softening as part of treatment.",
      "source_title": "St. Louis Water Division Consumer Confidence Report",
      "source_url": "https://www.stlwater.com/ccr.pdf",
      "evidence_ids": [
        "STLOUI-L-03"
      ]
    }
  },
  "sources_checked_on": "2026-10-27",
  "site": "https://stlouiswatersystems.com/",
  "brand": "St. Louis Water Systems by My Home Water System",
  "taking_requests": false
}