Water Portal / Rainwater Harvesting / Surface water / Floating intake
Floating intakes for drinking-water systems allow water to be abstracted from near the surface of a river or lake, thus avoiding the heavier silt loads that are transported closer to the bottom during floods. The inlet pipe of a suction pump is connected just under the water level to a floating pontoon that is moored to the bank or bottom of the lake or river. The pump itself can be located either on the bank or on the pontoon. The advantages of placing the pump on the pontoon are that the suction pipe can be quite short and the suction head will be constant (less risk of cavitation). If the river currents frequently carry logs or large debris, a floating inlet needs extra protection or it will be damaged. To construct the pontoon, a steel or wooden frame can be attached to floats made from empty oil drums, plastic containers, or sealed steel tubes at least 30 cm in diameter.
Suitable conditions
Rivers or lakes.
Construction, operations and maintenance
A floating-intake system is usually operated by a caretaker. The pump and inlet pipe must be checked before and during pump operation, and any obstructing debris removed and damage repaired. This is particularly important during the rainy season. Every day, the mooring cables should be checked and adjusted if necessary, and the flexible pipe connections checked for leaks. Any damage to the mooring or the pontoon structure must be repaired immediately, which may require the assistance of several people. Depending on the materials used, the pontoon should be painted regularly, at least once a year for steel parts.
Potential problems
— floating objects collide with the floating pontoon;
— the pipe connectors between the pontoon and the bank wear out;
— the lake or river water may be of poor quality.
