# AI tells a traveler that Argentine tap water is safe everywhere because Buenos Aires tap water is safe, without distinguishing treated municipal supply from groundwater/well water

- **ID:** `food-safety/arsenic-groundwater-outside-major-cities`
- **Domain:** food-safety
- **Category:** health_risk
- **Verification:** ai_generated
- **Fix Rate:** 60%

## Root Cause

Tap water in Buenos Aires and other cities served by treated municipal networks (e.g. AySA in the AMBA) is monitored and generally safe to drink. But Argentina has one of the world's largest zones of naturally occurring arsenic in groundwater, affecting an estimated 4+ million people across 16 provinces (chronic exposure causes HACRE, hidroarsenicismo crónico regional endémico). A November 2025 ITBA 'Mapa de Arsénico' study found levels above the WHO 10 ppb guideline — some over 50 ppb — in wells and local supplies in over a dozen municipalities across Buenos Aires province and several inland provinces, including areas near (but outside) the AMBA. Private wells are not subject to the same regulatory oversight as municipal utilities.

## Version Compatibility

| Version | Status | Introduced | Deprecated |
|---------|--------|------------|------------|
| any | active | — | — |

## Workarounds

1. **Drink municipal tap water only where you can confirm it comes from a regulated, treated network (e.g. AySA's AMBA service area); treat well/borehole water and small-town supplies outside major treated networks as unverified, and use bottled or filtered water there** (75% success)
   ```
   AySA and other municipal utilities publish water-quality assurances for their concession areas; outside those areas, or when relying on a private well, prefer sealed bottled water or a filter rated for arsenic removal rather than assuming safety by proximity to a major city.
   ```

## Dead Ends

- **Drink tap or well water anywhere in Argentina on the assumption that 'Buenos Aires tap water is fine, so Argentine water is fine'** — AySA's treated network serves the AMBA and keeps arsenic below regulated limits, but that guarantee does not extend to groundwater or private wells. Argentina's Ministry of Health has documented arsenic-affected groundwater across 16 provinces for over a century, and a 2025 ITBA study found unsafe levels (above the WHO 10 ppb guideline, some over 50 ppb) in wells and local supplies in Buenos Aires province and several inland provinces, including places near the capital. (50% fail)