Gravel Wetlands Pre-Filter Screen


Extend the operating life of a gravel wetland by filtering out trash and debris at the inlet.

wetland-filter-2The Pre-Filter Screen for gravel wetlands is a critical maintenance device that extends the operating life of a gravel wetland by filtering out trash and debris from the inlet. The gravel wetland pre-filter was designed to maximize the operating life of the gravel wetland, a BMP with exceptional nutrient and contaminant removal performance, pioneered at the UNH Stormwater Center.


The gravel wetland is a subsurface horizontal flow treatment wetland that benefits from pre-filtration at the perforated pipe inlets. The inlet standpipes can be prone to clogging by debris due to limited surface area of the pipe perforations 1%. When the standpipe clogs, the standpipes will bypass more frequently potentially allowing debris into the subsurface exfiltration pipes and increasing potential for clogging. The inlet pre-filter mounts over the standpipe to provide exceptional surface area (48%) and pre-filtration to reduce maintenance and extend the operating life of the gravel wetland.


The pre-filter enables the easy maintenance of the inlet in an easily accessible location with no special equipment required. The absence of a pre-filter may allow trash and debris to clog the perforated pipe in the exfiltration pipes within the gravel wetland. A clogged exfiltration manifold requires expensive maintenance by Hydro-jetting through cleanout.

The pre-filter installation is simple. The pre-filter has a collar which is fixed between corrugations on the standpipe. Installation is quick and takes less than 30 minutes requiring no special tools our training.

The pre-filter is made of aluminum and resistant to rust and rot from corrosive winter runoff.

The perforations are sized to be smaller than recommended perforations within a gravel wetland such that the exfiltration lines likelihood of clogging is greatly reduced.

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