{
  "city": "Baltimore",
  "state": "MD",
  "slug": "baltimore",
  "hardness_facts": [
    {
      "utility": "Baltimore City DPW (Montebello laboratory)",
      "measure": "Hardness, annual average of monthly results",
      "value_as_published": "114 mg/L (monthly range 109-120)",
      "period": "Calendar year 2022",
      "source_title": "Montebello Water Quality Laboratory Mineral Analyses 2022",
      "source_url": "https://publicworks.baltimorecity.gov/files/min-anal-2022pdf"
    },
    {
      "utility": "Baltimore City DPW (Ashburton laboratory)",
      "measure": "Hardness, annual average of monthly results",
      "value_as_published": "80 (monthly range 76-84; the form prints no unit)",
      "period": "Calendar year 2022",
      "source_title": "Ashburton Water Quality Laboratory Mineral Analyses 2022",
      "source_url": "https://publicworks.baltimorecity.gov/files/min-anal-2022-ashburton-labpdf"
    }
  ],
  "published_span_mg_per_l": [
    109,
    120
  ],
  "span_converted_from_grains": false,
  "usgs_class": "moderately hard",
  "usgs_class_source": "https://www.usgs.gov/water-science-school/science/hardness-water",
  "notes": [
    "The city's 2023, 2024 and 2025 water quality reports list no hardness figure, and we found no mineral analyses newer than 2022.",
    "The scale on this page uses the Montebello figures only, because the Ashburton form does not print a unit."
  ],
  "local_details": {
    "disinfectant": {
      "text": "Baltimore lists chlorine as the additive that disinfects its supply.",
      "kind": "chlorine",
      "source_title": "Baltimore City 2025 Water Quality Report",
      "source_url": "https://s3.amazonaws.com/baltimorecity.gov.if-us-east-1/s3fs-public/2026-07/2025%20Baltimore%20City%20Water%20Quality%20Report.pdf",
      "evidence_ids": [
        "BALTIM-L-01"
      ]
    },
    "source_water": {
      "text": "Baltimore water is rain and snowmelt stored in the Liberty, Loch Raven and Prettyboy reservoirs and treated at the Ashburton and Montebello plants. The Susquehanna River is used only in severe drought.",
      "source_title": "Baltimore City 2025 Water Quality Report",
      "source_url": "https://s3.amazonaws.com/baltimorecity.gov.if-us-east-1/s3fs-public/2026-07/2025%20Baltimore%20City%20Water%20Quality%20Report.pdf",
      "evidence_ids": [
        "BALTIM-L-02"
      ]
    }
  },
  "sources_checked_on": "2026-10-27",
  "site": "https://baltimorewatersystems.com/",
  "brand": "Baltimore Water Systems by My Home Water System",
  "taking_requests": false
}