{
  "city": "Chicago",
  "state": "IL",
  "slug": "chicago",
  "hardness_facts": [
    {
      "utility": "Chicago Department of Water Management",
      "measure": "Hardness as CaCO3, quarterly samples at both plants",
      "value_as_published": "129 to 158 mg/L",
      "period": "Three 2014 quarterly samplings (March, June and August 2014)",
      "source_title": "Chicago 2014 Comprehensive Chemical Analysis",
      "source_url": "https://www.chicago.gov/content/dam/city/depts/water/WaterQltyResultsNRpts/ccReports/cca14.pdf"
    }
  ],
  "published_span_mg_per_l": [
    129,
    158
  ],
  "span_converted_from_grains": false,
  "usgs_class": "hard",
  "usgs_class_source": "https://www.usgs.gov/water-science-school/science/hardness-water",
  "notes": [
    "The city's water quality reports for 2017 and 2021 through 2024 list no hardness figure, and its newer chemical analyses would not load for us, so the 2014 analysis is the newest published number we found.",
    "The 2014 figures cover raw and treated samples from both plants together."
  ],
  "local_details": {
    "disinfectant": {
      "text": "Chicago lists chlorine as its drinking water disinfectant.",
      "kind": "chlorine",
      "source_title": "Chicago 2024 Water Quality Report",
      "source_url": "https://www.chicago.gov/content/dam/city/depts/water/ConsumerConfidenceReports/2024_WaterQuality%20Report_CCR.pdf",
      "evidence_ids": [
        "CHICAG-L-01"
      ]
    },
    "source_water": {
      "text": "Chicago draws Lake Michigan water through offshore intakes to two plants: Jardine serves the north side and Sawyer the south side.",
      "source_title": "Chicago 2024 Water Quality Report",
      "source_url": "https://www.chicago.gov/content/dam/city/depts/water/ConsumerConfidenceReports/2024_WaterQuality%20Report_CCR.pdf",
      "evidence_ids": [
        "CHICAG-L-02"
      ]
    }
  },
  "sources_checked_on": "2026-10-27",
  "site": "https://chicagowatersystems.com/",
  "brand": "Chicago Water Systems by My Home Water System",
  "taking_requests": true
}