Resilience measure: Filter drain


A filter drain is a gravel filled trench, generally with a perforated pipe at the base. Runoff flows slowly through the granular material, trapping sediments and providing attenuation. Flow is then directed to a perforated pipe, which conveys run-off either back into the sewerage network or into a waterbody. Filter drains are mainly used to drain road and carpark surfaces. Ideally these systems are used as a component of a treatment train.
(Clifton Scannell Emerson Associates Limited, 2011, p. 38)

Co-benefits and impacts

Filter drains provide attenuation, limited treatment and minimal safety risk. Furthermore, they are relatively inexpensive, require low land take and can be used in most soil-conditions provided run-off discharges into a perforated pipe rather than to soil. Limitation of the filter drains are that no habitat or amenity value provided, they do not provide any biological treatment, since they are subsurface structures, operational problems are not always visible and they require regular maintenance.
(Clifton Scannell Emerson Associates Limited, 2011, p. 38)


Filter drain are not suitable where groundwater levels are high, i.e. likely to come within 1.5m of the base of the device and they are not suitable for industrial areas unless treatment is provided upstream of the device and operates as part of a treatment train.
(Clifton Scannell Emerson Associates Limited, 2011, p. 38)

Related Links

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Medium term

Synonym of Resilience Measures (Show all)

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Filter trench

Last modified: Sept. 21, 2016, 8:24 a.m.