AttenuationTanks Range

An attenuation tank temporarily holds surface water run-off from roofs, driveways or hardstanding before releasing it at a controlled rate into a sewer, watercourse or soakaway. They're typically required where a site's discharge rate must be restricted as part of a SuDS (Sustainable Drainage System) strategy, often stipulated by the local authority or water company as a planning condition. This prevents flooding and eases pressure on downstream drainage infrastructure.

Sizing depends on the catchment area draining into the system, the local rainfall intensity, the ground's soakaway capacity (if applicable) and the permitted discharge rate set by the water authority or drainage engineer. Most projects require a drainage calculation, often carried out by a civil or drainage engineer using standard software, to confirm the required storage volume in litres. We can help match a calculated volume to a suitable Klargester tank, but the calculation itself should come from your drainage designer.

GRP (glass-reinforced plastic) tanks offer a single, structurally proven vessel with a known, guaranteed storage volume, unlike modular crate systems which can be prone to silting, collapse under poor installation, or require extensive geotextile wrapping. A Klargester GRP tank is also faster to install than a large network of oversized pipes, needs a smaller excavation footprint for the same capacity, and comes with straightforward inlet/outlet connections already configured.

Yes, GRP attenuation tanks can be installed beneath trafficked areas, but this depends on burial depth, backfill material and whether a suitable load-spreading slab or surround is used as specified by the manufacturer. You'll need to confirm the expected traffic loading (pedestrian, car or heavy goods vehicle) at enquiry stage so the correct tank specification and installation method is used. Ground conditions and water table should also be assessed before installation.

Tanks are supplied with inlet and outlet connections positioned and sized to suit your drainage layout, and orientation can be specified at order stage to avoid unnecessary pipe runs or bends on site. A flow control device — such as a vortex or orifice plate control — is usually fitted at the outlet to restrict discharge to the rate approved by the water authority. It's worth confirming pipe sizes and invert levels against your drainage drawings before ordering.

Yes, attenuation tanks should be inspected periodically to check for silt build-up, particularly if surface water run-off carries debris from roads or unpaved areas, as this can reduce storage capacity and clog the flow control. Access covers are fitted at ground level to allow inspection and, where necessary, jetting or vacuum tanker clean-out. A simple annual check is usually sufficient for most domestic and light commercial installations.