{
 "sources": {
  "MDH": "https://www.health.state.mn.us/communities/environment/hazardous/topics/pfashometreat.html",
  "NSF-PFAS": "https://www.nsf.org/consumer-resources/articles/pfas-drinking-water",
  "NSF-FOREVER": "https://www.nsf.org/knowledge-library/forever-chemicals-advancement-filtration-standards",
  "NSF-42-53-401": "https://www.nsf.org/knowledge-library/nsf-ansi-42-53-and-401-filtration-systems-standards",
  "NSF-58": "https://www.nsf.org/knowledge-library/nsf-ansi-58-reverse-osmosis-drinking-water-treatment-systems",
  "ANSI-STDS": "https://blog.ansi.org/ansi/nsf-ansi-drinking-water-treatment-standards/",
  "EPA-LEAD-FILTERS": "https://www.epa.gov/water-research/consumer-tool-identifying-point-use-and-pitcher-filters-certified-reduce-lead",
  "EPA-WATERSENSE": "https://www.epa.gov/system/files/documents/2024-11/ws-products-home-water-treatment-guide_508.pdf",
  "EPA-PFAS-TREAT": "https://www.epa.gov/system/files/documents/2024-04/pfas-npdwr_fact-sheet_treatment_4.8.24.pdf",
  "EPA-PFAS-FILTERS": "https://www.epa.gov/water-research/identifying-drinking-water-filters-certified-reduce-pfas"
 },
 "rows": [
  {
   "id": "pfas",
   "contaminant": "PFAS (PFOA, PFOS, PFHxS, PFNA, HFPO-DA)",
   "data_field": "ucmr5 *_max_sp_avg_ppt vs EPA Table 4 thresholds",
   "technologies": [
    "Activated carbon (GAC) - NSF/ANSI 53 PFAS claim",
    "Reverse osmosis - NSF/ANSI 58 PFAS claim",
    "Anion exchange (certified under 53)"
   ],
   "standard": "NSF/ANSI 53 (carbon, ion exchange) and 58 (RO); the former NSF P473 PFOA/PFOS protocol was folded into 53 and 58",
   "whole_house": "PARTIAL / NOT PROVEN TO MCL. Whole-house (point-of-entry) carbon is used by states for PFAS, usually two vessels in series, but the certification claim is <20 ppt combined PFAS, above the 4 ppt PFOA/PFOS MCL. Softeners and iron filters do not remove PFAS.",
   "point_of_use": "RO (NSF/ANSI 58 PFAS-certified) or carbon block (NSF/ANSI 53 PFAS-certified) at the drinking tap; same <20 ppt certification limit.",
   "caveats": [
    "No NSF/ANSI certification yet demonstrates reduction to the 4 ppt MCL (per MN Dept of Health and NSF).",
    "Carbon needs scheduled media change; breakthrough of short-chain PFAS comes first.",
    "A home test by an accredited lab is the only way to know what your tap contains."
   ],
   "sources": [
    "MDH",
    "NSF-PFAS",
    "NSF-FOREVER",
    "EPA-PFAS-TREAT",
    "EPA-PFAS-FILTERS"
   ]
  },
  {
   "id": "lead",
   "contaminant": "Lead",
   "data_field": "pb90_mgl (90th percentile, latest SDWIS sampling period)",
   "technologies": [
    "Point-of-use carbon block / pitcher certified for lead",
    "Reverse osmosis"
   ],
   "standard": "NSF/ANSI 53 (lead reduction) or 58",
   "whole_house": "NO. Lead mostly enters from the home service line and plumbing after the point of entry, so a whole-house filter does not address it; use a certified point-of-use filter at the tap.",
   "point_of_use": "Choose a filter certified to NSF/ANSI 53 for lead (EPA consumer tool).",
   "caveats": [
    "Certification is model specific; check the listing."
   ],
   "sources": [
    "EPA-LEAD-FILTERS",
    "NSF-42-53-401"
   ]
  },
  {
   "id": "chlorine",
   "contaminant": "Chlorine taste and odor (aesthetic)",
   "data_field": "not computed (SDWIS has no tap chlorine levels)",
   "technologies": [
    "Activated carbon (granular or block)"
   ],
   "standard": "NSF/ANSI 42",
   "whole_house": "YES for free chlorine taste/odor with sized carbon tank.",
   "point_of_use": "Yes.",
   "caveats": [
    "Aesthetic claim only; NSF 42 is not a health claim."
   ],
   "sources": [
    "NSF-42-53-401",
    "EPA-WATERSENSE"
   ]
  },
  {
   "id": "chloramine",
   "contaminant": "Chloramine",
   "data_field": "not computed",
   "technologies": [
    "Catalytic carbon"
   ],
   "standard": "NSF/ANSI 42 (only if the product listing claims chloramine reduction)",
   "whole_house": "YES if the product is listed for chloramine; ordinary carbon is less effective.",
   "point_of_use": "Yes if listed.",
   "caveats": [
    "Verify the specific NSF listing."
   ],
   "sources": [
    "EPA-WATERSENSE"
   ]
  },
  {
   "id": "nitrate",
   "contaminant": "Nitrate / nitrite",
   "data_field": "hb_viol_5y_by_group[nitrate]",
   "technologies": [
    "Reverse osmosis",
    "Anion exchange (nitrate-selective)"
   ],
   "standard": "NSF/ANSI 58 (nitrate/nitrite reduction listing) or 53",
   "whole_house": "LIMITED. Carbon does not remove nitrate; anion exchange can treat whole-house but needs resin regeneration and brine handling.",
   "point_of_use": "RO certified for nitrate/nitrite.",
   "caveats": [
    "Bacterial and infant (blue-baby) risk: use bottled or RO water for infant formula if nitrate exceeds the MCL."
   ],
   "sources": [
    "NSF-58",
    "EPA-WATERSENSE"
   ]
  },
  {
   "id": "arsenic",
   "contaminant": "Arsenic",
   "data_field": "hb_viol_5y_by_group[arsenic]",
   "technologies": [
    "Reverse osmosis",
    "Activated alumina / specialty media"
   ],
   "standard": "NSF/ANSI 58 (pentavalent arsenic) or 53",
   "whole_house": "LIMITED. Needs pre-oxidation (As III to As V) and specialty media; not an off-the-shelf carbon job.",
   "point_of_use": "RO certified for arsenic V.",
   "caveats": [
    "Verify certified arsenic species."
   ],
   "sources": [
    "NSF-58",
    "EPA-WATERSENSE"
   ]
  },
  {
   "id": "hardness",
   "contaminant": "Hardness (scale)",
   "data_field": "not computed",
   "technologies": [
    "Ion-exchange water softener"
   ],
   "standard": "NSF/ANSI 44",
   "whole_house": "YES (this is what whole-house softeners are for).",
   "point_of_use": "n/a",
   "caveats": [
    "Softeners add sodium and discharge brine; they do not remove PFAS, lead or nitrate."
   ],
   "sources": [
    "EPA-WATERSENSE",
    "ANSI-STDS",
    "MDH"
   ]
  },
  {
   "id": "microbes",
   "contaminant": "Bacteria / viruses (private wells)",
   "data_field": "hb_viol_5y_by_group[coliform_bacteria, surface_water_treatment...]",
   "technologies": [
    "UV disinfection"
   ],
   "standard": "NSF/ANSI 55",
   "whole_house": "YES for microbial inactivation only, with clear (low turbidity) water. UV does nothing for chemicals.",
   "point_of_use": "Yes.",
   "caveats": [
    "Public utilities already disinfect; UV matters mostly for private wells."
   ],
   "sources": [
    "ANSI-STDS",
    "EPA-WATERSENSE"
   ]
  },
  {
   "id": "dbp",
   "contaminant": "Disinfection byproducts (TTHM/HAA5)",
   "data_field": "hb_viol_5y_by_group[disinfection_byproducts]",
   "technologies": [
    "Activated carbon"
   ],
   "standard": "NSF/ANSI 53 (VOC/THM claim)",
   "whole_house": "PARTIAL. Carbon can reduce THMs; check the certified claim.",
   "point_of_use": "Yes at the tap.",
   "caveats": [
    "Unverified for HAA5 specifically."
   ],
   "sources": [
    "NSF-42-53-401"
   ]
  },
  {
   "id": "emerging",
   "contaminant": "Pharmaceuticals, pesticides (trace organics)",
   "data_field": "not computed",
   "technologies": [
    "Activated carbon"
   ],
   "standard": "NSF/ANSI 401 (up to 15 listed compounds)",
   "whole_house": "n/a - claims are product specific.",
   "point_of_use": "Yes if listed.",
   "caveats": [
    "Not tied to utility data on this site."
   ],
   "sources": [
    "NSF-42-53-401",
    "ANSI-STDS"
   ]
  },
  {
   "id": "lithium",
   "contaminant": "Lithium",
   "data_field": "lithium_max_ugl vs EPA 10 ug/L reference (UCMR 5 rounding rule: >15 counts as above)",
   "technologies": [
    "UNVERIFIED"
   ],
   "standard": "None found",
   "whole_house": "UNVERIFIED - no filter certification claim located. Do not make filter claims.",
   "point_of_use": "UNVERIFIED",
   "caveats": [
    "EPA reference concentration is non-regulatory."
   ],
   "sources": []
  },
  {
   "id": "kdf",
   "contaminant": "KDF media (copper-zinc)",
   "data_field": "n/a",
   "technologies": [
    "KDF 55/85"
   ],
   "standard": "UNVERIFIED",
   "whole_house": "UNVERIFIED - no authoritative source collected; do not recommend on site until sourced.",
   "point_of_use": "UNVERIFIED",
   "caveats": [],
   "sources": []
  }
 ]
}