{"hq_id":"hq-p-fod-000119","name":"Emergency Water Purification Tablets — Chlorine Dioxide, Iodine, and NaDCC Formulations for Disaster and Backcountry Use (Potable Aqua, Aquatabs, Katadyn Micropur)","category":{"primary":"water_quality","secondary":"emergency_water","tags":["water purification tablets","chlorine dioxide","iodine","NaDCC","emergency","disaster","backcountry","Potable Aqua","Aquatabs","Katadyn","Cryptosporidium"]},"product_tier":"FOD","overall_risk_level":"low","description":"Emergency water purification tablets are critical tools for disaster preparedness, military field operations, and backcountry recreation, providing chemical disinfection of microbiologically unsafe water without electricity or complex equipment. Three primary chemistries dominate: (1) Sodium dichloroisocyanurate (NaDCC, Aquatabs) — releases free chlorine at 1-2 mg/L, effective against bacteria and viruses in 30 minutes but limited against Cryptosporidium oocysts; (2) Iodine-based tablets (Potable Aqua, tetraglycine hydroperiodide) — releases 8 mg/L elemental iodine, effective in 30 minutes at warm temperature, but contraindicated in pregnancy, thyroid disease, and shellfish allergy, with iodine taste and color objectionable to many users; (3) Chlorine dioxide tablets (Katadyn Micropur MP1, Aquamira) — generates 0.5-4 mg/L ClO2, the only chemical method effective against Cryptosporidium oocysts (4-hour contact time), and the method recommended by the EPA for broadest-spectrum field disinfection. All chemical methods are less effective in cold (<5C), turbid (>10 NTU), or highly organic water. Pre-filtration through a cloth or coffee filter improves efficacy dramatically.","synthesis":{"derived_risk_level":"moderate_to_high","synthesis_confidence":0.5,"synthesis_method":"compound_composition","context_used":"human_child","context_source":"product_users","exposure_modifier":1,"vulnerability_escalated":true,"escalation_reason":"Child exposure group","compounds_resolved":1,"compounds_total":1,"synthesis_date":"2026-05-09","synthesis_version":"1.2.0","methodology_note":"exposure_modifier and adjusted_magnitude are computed from ALETHEIA-calibrated heuristics (route × duration × frequency multipliers, clamped to [0.5, 1.4]). Multipliers are directionally informed by EPA Exposure Factors Handbook (2011) and CalEPA OEHHA but are not regulatory consensus. See /api/methodology for full disclosure."},"hazard_summary":{"sensitive_populations":"pregnant women and thyroid disease patients (iodine tablets contraindicated), children (iodine dose-to-weight ratio), immunocompromised individuals who require Cryptosporidium protection","overall_risk":"low","primary_concerns":["Iodine tablets contraindicated in pregnancy, thyroid disease, and iodine allergy","NaDCC (chlorine) tablets do NOT inactivate Cryptosporidium oocysts — false sense of security in Crypto-risk water","Cold water (<5C) and turbid water (>10 NTU) significantly reduce disinfection efficacy","Insufficient contact time (most common user error) results in incomplete pathogen inactivation"],"exposure_routes":"Ingestion (drinking chemically treated water containing residual disinfectant)."},"exposure":{"routes":["ingestion"],"contact_types":["ingestion_acute"],"users":["adult","child","military_personnel"],"duration":"acute","frequency":"emergency_or_recreational","scenarios":["Disaster: municipal water system failure — household uses NaDCC tablets for emergency drinking water","Backcountry: hiker treats stream water with chlorine dioxide tablets (4-hour wait for Cryptosporidium inactivation)","Military: iodine tablets for rapid field water disinfection in austere environments","Improper use: insufficient contact time or cold water temperature reduces disinfection efficacy"],"notes":"NaDCC (sodium dichloroisocyanurate): CAS 2893-78-9; releases HOCl (free chlorine). WHO recommends for household water treatment in emergencies. Aquatabs: 17 mg NaDCC per tablet treats 1L. Ct value for 3-log virus inactivation: ~4 mg-min/L at pH 7. Not effective against Cryptosporidium (oocyst wall resistant to chlorine). Iodine (tetraglycine hydroperiodide): releases ~8 mg/L I2. Effective against bacteria and viruses; partially effective against Giardia (30-min at 25C). NOT effective against Cryptosporidium. Contraindications: thyroid disease, pregnancy, allergy to iodine. Max recommended use: 2-3 weeks continuous. Chlorine dioxide (ClO2): generated from sodium chlorite + acid activation. Unlike free chlorine, ClO2 effectively inactivates Cryptosporidium (Ct ~78 mg-min/L for 2-log). 4-hour contact time recommended by Katadyn. EPA MRDL for ClO2: 0.8 mg/L."},"consumer_guidance":{"usage_warning":"Follow tablet instructions EXACTLY — contact time, water temperature, and water clarity all affect disinfection. For Cryptosporidium protection, use chlorine dioxide tablets (NOT iodine or NaDCC chlorine tablets) with a 4-hour wait time. Pre-filter turbid water through cloth or coffee filter before adding tablets. Do not use iodine tablets if you are pregnant, have thyroid disease, or are allergic to iodine. Iodine tablets should not be used as a sole water treatment for more than 2-3 weeks. Store tablets in original sealed packaging away from heat and moisture — degraded tablets lose potency.","safer_alternatives":["Chlorine dioxide tablets (Katadyn Micropur MP1) for broadest-spectrum protection including Cryptosporidium","Portable water filter + UV SteriPEN combination (filtration + UV for multi-barrier approach)","Boiling (1 minute rolling boil at sea level, 3 minutes above 6,500 ft — most reliable field method)","Portable gravity or pump filter certified for protozoa + bacteria (0.2 micron) combined with chemical treatment for viruses"]},"regulatory":{"applicable_regulations":[{"jurisdiction":"USA","regulation":"EPA Registration of Water Purification Products Under FIFRA + NSF 60","citation":"FIFRA Section 3 (EPA Registration for antimicrobial claims); NSF/ANSI 60 (Drinking Water Treatment Chemicals)","requirements":"Water purification tablets making antimicrobial claims must be EPA-registered under FIFRA. Products used for public water treatment must meet NSF/ANSI 60 (Drinking Water Treatment Chemicals — Health Effects). Emergency/field-use tablets are EPA-registered as pesticide devices or antimicrobial products. WHO prequalifies NaDCC tablets for emergency household water treatment (Aquatabs has WHO prequalification).","compliance_status":null,"effective_date":null,"enforcing_agency":"EPA Office of Pesticide Programs; WHO (international)","penalties":null,"source_ref":null}],"certifications":[],"labeling":{"required_disclosures":[],"prop65_warning":{"required":null,"chemicals":[],"endpoint":null,"notes":null},"ghs_labeling":{"required":null,"signal_word":null,"pictograms":[],"hazard_statements":[],"notes":null},"hidden_ingredients":{"trade_secret_protected":null,"categories_hidden":[],"estimated_count":null,"known_concerns":null,"notes":null},"notes":null},"recalls":[],"regulatory_gap":null,"notes":null},"lifecycle":{"recyclable":false,"disposal_guidance":"Unused tablets in sealed packaging: store for 3-5 years. Opened/expired tablets: dispose in household trash. Treated water residual chlorine/iodine dissipates within hours.","hazardous_waste":false,"expected_lifespan":"Sealed tablets: 3-5 year shelf life (NaDCC, ClO2); iodine tablets: 4 years sealed, use within 1 year of opening"},"formulation":{"form":"varies","key_ingredients":[],"certifications":[]},"materials":{"common":[],"concerning":[],"preferred":[]},"compound_composition":[{"hq_id":"hq-c-org-002022","compound_name":null,"role":"active_disinfectant","typical_concentration":"chlorine dioxide generated at 0.5-4 mg/L; EPA-approved disinfectant effective against bacteria, viruses, and Cryptosporidium (4-hour contact)"}],"identifiers":{"common_names":["emergency water purification tablets — chlorine dioxide, iodine, and nadcc formulations for disaster and backcountry use (potable aqua, aquatabs, katadyn micropur)"],"aliases":[],"manufacturer":null,"brands":[]},"brand_examples":[],"brand_examples_disclaimer":null,"sources":[{"type":"expert_curation","name":"ALETHEIA Safety Database","date":"2026-03-26"}],"meta":{"schema_version":"4.0.0","last_updated":"2026-03-26","timestamp":"2026-06-02T21:31:38.022Z"}}