Is Tap Water Safe to Drink in Sri Lanka?

The National Water Supply and Drainage Board (NWSDB), established in 1975, serves 41.3% of the population through 2.4 million domestic connections supplying 2.5 million m³ daily. The Kelani River is the primary source for Greater Colombo, feeding the Ambatale and Biyagama water treatment plants. About 80% of rural households rely on groundwater via wells and hand pumps.

Microbial contamination (E. coli, Giardia, Cryptosporidium, hepatitis A) is the primary concern, especially in untreated rural sources. Chronic Kidney Disease of unknown etiology (CKDu) affects 5–20% of adults in endemic regions, linked to elevated glyphosate (found in 44% of endemic-area wells), fluoride, and heavy metals in groundwater. Agricultural runoff pollutes the Kelani River basin.

Colombo and Western Province have the softest water (under 60 mg/L hardness) but elevated organic pollution. The Dry Zone (Anuradhapura, Hambantota, Jaffna) has very hard water and the worst CKDu prevalence. Nationally, 42.2% of well water is classified as very hard (above 180 mg/L).

Highly variable: Colombo area is soft at under 60 mg/L, but Dry Zone areas (Hambantota, Anuradhapura) are very hard, commonly exceeding 180 mg/L. National well-water average skews hard.

A 2021 household survey found 21.6% of households boil water, 9.1% use filters, and 67.1% apply no treatment. Locals in urban areas have greater tolerance to local microbiota, but boiling remains a common precaution.

• •Drink only bottled, boiled, or filtered water throughout Sri Lanka
• •Use bottled water for brushing teeth
• •Higher risk in rural areas, flood-prone regions, and older buildings with rooftop storage tanks

• •Drink only bottled, boiled, or properly filtered water
• •Use bottled water for brushing teeth
• •Avoid ice unless confirmed purified