The overnight shutdown that cut water to parts of Colombo and Gampaha began with residents of Heiyanthuduwa noticing that water running through a paddy field had turned a vivid blue.

The National Water Supply and Drainage Board (NWSDB) has now confirmed the cause was the release of a chemical into the environment by a private industrial premises, Ada Derana and the Daily Mirror reported on Tuesday. Both outlets described the source as a private factory; NewsFirst, which reported from the site, identified it as a container yard.

Residents followed the water for a kilometre and a half

By the account residents gave NewsFirst, they spotted the discoloured water on Monday afternoon and traced its path roughly 1.5 kilometres upstream to a drain connected to a container yard on Samurdhi Mawatha.

“We felt that something had mixed with the water, possibly a chemical,” one resident said. They alerted Public Health Inspectors and police. Another resident said that on entering the premises they saw soil being spread over the affected area, “apparently to cover the leaked substance.”

The drain feeds the Kottunna Oya, which reaches the Kelani River through Raggahawatta. NewsFirst put the yard about 3.5 kilometres from the nearest point of the river; the Kelani South Bank plant at Biyagama sits roughly 2.5 kilometres from the adjacent river point, and Ambatale about 3.5 kilometres.

A solution used to make rubber gloves — but no name

Representatives at the yard told NewsFirst that a container carrying a solution used in the manufacture of rubber gloves had recently arrived, that a leak was detected before it entered the premises, and that workers moved the vehicle inside and cleaned the empty container. Rainwater, they said, later carried some of the liquid outside.

Asked directly what the substance was, the company declined to identify it. That leaves the central question of the incident unanswered: what entered the Kottunna Oya, and in what quantity.

Police complaint lodged

NWSDB Chairman Chandana Bandara said laboratories were opened and samples tested through the night at points along the Kelani before the Ambatale and Biyagama plants restarted at about 4.30 a.m. Testing confirmed the water meets required standards.

Bandara said the Board has lodged a complaint with police and that the relevant authorities have been informed to take appropriate legal action. A joint investigation is being conducted by the Disaster Management Centre and the security forces.

The Daily Mirror reported supply returning to Colombo areas by 7 a.m., to Biyagama, Kelaniya and Gampaha from around 6 a.m., and to Kotte, Battaramulla and Wellawatta by about 9 a.m.

No outlet has reported whether the company faces action under environmental law, or named it.

Update: contaminated soil to be dug out and destroyed — August 26

The Ministry of Environment said on Wednesday that steps have been taken to collect and destroy the layers of soil contaminated by the chemical that flowed from the container yard into the paddy fields, NewsFirst reported. The ministry said an investigation is also under way.

The announcement puts a second state body onto the incident alongside the Water Board’s police complaint, and confirms that the contamination was judged serious enough to require physically removing the affected soil rather than leaving it to disperse — the first indication of the leak’s scale on land, as opposed to its effect on the water supply.

NewsFirst described the leaked material as a chemical solution used for rubber gloves, consistent with what yard representatives told the outlet a day earlier. The ministry has still not named the substance, said how much soil is to be removed, where it will be destroyed, who bears the cost, or when the work begins. The company remains unnamed by any outlet.

Sources