Pazhassi Dam Silt Disrupts Kannur Water Supply as Turbidity Hits 125 NTU
Heavy silt inflow into the Pazhassi dam, triggered by intense rainfall and landslips in its catchment area, disrupted drinking water treatment on Sunday (August 2, 2026), leading to a reduced water supply in parts of Kannur and adjoining regions.
The Pazhassi dam is a vital source of raw water for the region. Located in the eastern part of Kannur district, it is fed by streams originating in the forested hills of the Western Ghats. During the south-west monsoon, these hills often experience landslips that carry large amounts of soil and debris into the reservoir.
Kerala Water Authority (KWA) officials clarified that the issue was not contamination but unusually high turbidity caused by excessive mud content in the raw water. The water could be treated safely only after turbidity levels decline, they said.
Turbidity is a measure of the cloudiness of water, determined by the amount of suspended particles such as silt, clay, or organic matter. The standard unit used in India is the Nephelometric Turbidity Unit (NTU). At the Pazhassi water treatment plant, turbidity was measured at around 125 NTU on Saturday night, while efficient treatment is possible only when it falls below 50 NTU.
A senior KWA official explained the implications of high turbidity. “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,” he told The Hindu.
In conventional water treatment plants, raw water is first mixed with coagulants to make particles clump together. The heavier flocs then settle in clarifiers, and the clearer water passes through filters. When the incoming water is excessively turbid, the flocs form too quickly and clog the filters within hours, drastically reducing the plant’s output. This is why KWA decided to pause operations rather than supply partially treated water.
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.
The Pazhassi treatment plant supplies around 30 million litres per day (MLD) of drinking water to Kannur town and surrounding areas, including Valapattanam and Chirakkal. The disruption has led to water scarcity in these areas, forcing residents to rely on stored water or alternate sources.
According to KWA officials, the muddy water is the result of landslides and heavy runoff in the forested upper catchments, reportedly in the neighbouring state of Karnataka, which feed the dam. Continued rainfall could prolong the problem by keeping turbidity levels elevated.
Officials advised consumers in the affected areas to use stored water judiciously until normal pumping resumes. They also said that the disruption is expected to ease once rainfall subsides and the raw water becomes clearer.
High turbidity is not just a technical inconvenience. It can interfere with the disinfection process, as suspended particles may harbour micro-organisms and shield them from chlorine. It also affects the taste and appearance of water. However, KWA has reassured residents that the current issue is due to physical silt, not chemical or biological contamination, and that treated water will be safe for consumption.
The incident highlights the fragility of water supply systems in the face of extreme weather events, which are becoming more frequent due to changing climate patterns. It also underscores the need for investment in catchment protection and silt management to prevent such disruptions in the future. As monsoon rains continue, KWA officials remain on high alert to restore normal water supply as quickly as possible.
