Is Tap Water Safe to Drink in Comoros?

Moroni on Grande Comore depends heavily on rainwater catchment and groundwater wells, since the island's porous volcanic rock allows rain to drain away quickly, leaving few permanent rivers. Anjouan and Mohéli have somewhat more surface water but still rely on a patchwork of small treatment stations, communal wells, and rainwater tanks with inconsistent chlorination.

Bacterial contamination from inadequate sanitation near wells and cisterns is common, and cholera risk rises periodically in densely populated coastal areas. Saltwater intrusion into coastal aquifers during dry periods also raises salinity in some groundwater wells, particularly on Grande Comore.

Moroni has the most developed, though still limited, water infrastructure, while smaller towns and villages across all three islands depend heavily on household rainwater cisterns and shared wells. Mohéli, the least developed island, has the most limited access to any treated water.

Rainwater-fed household supply is very soft, typically under 50 mg/L, while coastal groundwater wells affected by saline intrusion can be significantly harder, sometimes exceeding 300 mg/L..

Many Comorian households rely on rainwater cisterns and treat water informally by boiling, given limited access to a centrally treated municipal supply.

• •Drink only bottled or boiled water throughout Comoros
• •Avoid water from household rainwater cisterns unless it has been treated
• •Bring water purification tablets for island-hopping trips to Anjouan and Mohéli
• •Check with lodges about their water source before drinking directly

• •Treat or boil rainwater and well water before drinking
• •Avoid coastal wells during dry season when salinity tends to rise