Heavy silt in Pazhassi dam disrupts drinking water treatment

Heavy silt inflow into the Pazhassi dam following intense rain and landslips in the catchment disrupted drinking water treatment, reducing water supply to parts of Kannur and adjoining areas on Sunday (August 2, 2026).

Kerala Water Authority (KWA) officials said the issue was not contamination but unusually high turbidity caused by excessive mud content in the raw water. They added that the water could be treated safely only after turbidity levels declined. At the Pazhassi water treatment plant, turbidity was measured at around 125 Nephelometric Turbidity Units (NTU), whereas efficient treatment is possible only when it falls below 50 NTU.

A senior KWA official said NTU measures the cloudiness, or turbidity, of water by indicating how suspended particles scatter light. Higher NTU values indicate muddier water, while lower values indicate clearer water. “The issue is not that the water cannot be treated. When turbidity is very high, the treatment capacity drops sharply and the filters clog quickly,” the official told The Hindu.

The official said water treatment was suspended after tests conducted on Saturday (August 1, 2026) night showed excessive turbidity. Engineers are monitoring water quality every hour, and pumping will resume once turbidity levels fall to safer limits, he added.

The Pazhassi treatment plant supplies around 30 million litres a day (MLD) of drinking water to Kannur town and surrounding areas, including Valapattanam and Chirakkal. The disruption has affected water supply in these areas.

According to KWA officials, the muddy water is the result of landslides and heavy runoff in the forested upper catchments, reportedly in Karnataka, that feed the Pazhassi dam. Continued rainfall could prolong the problem by keeping turbidity levels high.

Officials said the situation would improve if rainfall subsides and advised consumers to use stored water judiciously until normal pumping resumes. They added that the disruption was expected to ease once the raw water became clearer.