Screening and straining


Water filtration method using screens or sieves made of steel with a mesh-size of 2-8cm. Often placed at surface water inlets to prevent debris or coarse material from reaching subsequent treatment processes. Microstrainers with openings of 10-60┬Ám can be applied after screens for the removal of algae.


Costs depend on the design and the cleaning mechanism applied. Expenses can be kept low by using manual labor for cleaning and maintenance. Typically an affordable solution, but specific costs are difficult to offer as they strongly depend on region.


Applied at (inlet of) central treatment facilities, but simple use makes it suitable for decentralized applications. Management requirements depend on cleaning mechanism. Maintenance is low, can be combined with cleaning of other facilities. Training on debris management might be required.


Applied for surface water containing coarse particles and at tank inlets of roof top water harvesting systems.. Debris mostly includes organic material like leaves, duckweed and algae. In vicinity of urban settlements, plastic wastes are typical. Debris needs to be properly disposed and managed according to its characteristics and volume.


A simple, but flexible technology for diverse configurations. Straight screens can be manufactured locally and cleaned manually. Cylindrical or drum strainers require mechanical cleaning (backwashing). Requires regular debris removal. Lower debris load reduces cleaning frequency.


Requires no specific social campaign as the method is widespread and is not applied directly at household level. Screening only removes larger particles, therefore it cannot guarantee safe water quality. To be applied in combination with other treatment processes.

Relevant remarks:

No relevant remarks for Screening and straining.