The Dar es Salaam Water Supply and Sanitation Authority (Dawasa) has identified more than 20 areas where water infrastructure could be affected by heavy El Niño rains expected in Dar es Salaam and Coast regions. Dawasa is taking proactive measures to protect water sources, treatment plants, major transmission pipelines, and sewerage systems from flooding, erosion, and other damage. This move aims to minimize disruptions to water supply services during the anticipated heavy rainfall period.
The Tanzania Meteorological Authority (TMA) has forecast above-average to average rainfall in several regions during the October-December period, including Dar es Salaam, Coast, Tanga, Morogoro, Arusha, Kilimanjaro, and parts of Zanzibar. Dawasa Chief Executive Officer Mkama Bwire said heavy rains could increase water availability but also affect production and distribution infrastructure. The Ruvu River, which supplies a large proportion of the water distributed to residents, is expected to receive more water.
More than 90 percent of Dawasa's water production comes from surface water sources, mainly major rivers. The Ruvu River is the authority's main source, while other sources include the Wami River and groundwater wells in Kigamboni. However, heavy rainfall can increase riverbank erosion and wash soil and debris into water intake points, affecting treatment processes. Dawasa is working with the Wami-Ruvu Basin Water Board to identify vulnerable areas and reinforce riverbanks before rainfall intensifies.
Dawasa is preparing treatment plants for increased raw-water flows and higher levels of sediment. Heavy rains could increase the amount of silt entering treatment plants, raising the quantity of chemicals needed to treat water. The authority normally spends about Sh1.5 billion a month on water-treatment chemicals, and this cost could rise significantly during periods of heavy rainfall. To mitigate this, Dawasa has increased its stock of treatment chemicals and engaged suppliers to ensure adequate supplies during the rainy season.
Major pipelines carrying treated water from the Ruvu plants to Dar es Salaam have been assessed, particularly where they cross rivers and other flood-prone areas. The Mpiji River, along the Dar es Salaam-Coast border, is one of the areas receiving special attention because major water pipelines pass close to the river. Dawasa has assessed vulnerable sections and is strengthening riverbanks and protecting pipelines against floodwater.
The authority has improved infrastructure in areas previously affected by flooding, including Selander Bridge and Jangwani. At Selander Bridge, some pipelines have been raised to reduce their exposure to floodwater, while others in Jangwani have been relocated and reinforced. Dawasa has prepared specific response plans for more than 20 vulnerable locations and stocked emergency materials, including replacement pipes.
The measures are intended to reduce the time needed to restore water services if pipelines or other infrastructure are damaged by flooding or erosion. In Boko and other strategic areas, emergency materials are already available for quick deployment if infrastructure is damaged. With these preparations, Dawasa aims to ensure a stable water supply to residents despite the anticipated El Niño rains.
Key points
- Dawasa has identified over 20 areas at risk from expected El Niño rainfall.
- The authority is preparing treatment plants for increased raw-water flows and higher levels of sediment.
- Dawasa has improved infrastructure in areas previously affected by flooding.
