Catchpits play a vital role in preventing blockages and water contamination in drainage systems. Without them, water could back up and cause localised flooding.
Here’s our quick guide to how catchpits work and why they’re essential for effective surface water management.
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What is a Catchpit?
A catchpit is an empty chamber installed within a drainage system to trap silt and debris before it can enter the main drainage network. By collecting these materials, catchpits prevent blockages that could lead to water backing up and causing flooding.
In contrast to a soakaway system, which allows collected water to gradually percolate back into the ground, a catchpit captures solids before water flows further through the drainage network.
Where are Catchpits used?
Catchpits are found in a variety of wastewater and surface water management systems — from mainline sewers to highway drainage, car parks, railways, and agricultural land drainage schemes.
How does a Catchpit work?
A catchpit has an inlet pipe that sits higher than its outlet pipe. As water flows into the chamber, gravity causes heavier silt and debris to settle at the bottom — known as the sump.
The cleaner water exits through the lower outlet pipe, which may be fitted with a baffle or filter to prevent floating debris from escaping. Over time, the sump collects sediment and needs regular cleaning to maintain efficiency. If neglected, debris build-up can lead to system blockages and localised flooding.
What are Catchpits made from?
Historically, catchpits were brick-lined, but modern systems are typically made from precast concrete (PCC) or high-density polyethylene (HDPE).
PCC catchpits come in a range of sizes with different inlet and outlet configurations, allowing for efficient on-site installation.
HDPE catchpits are lighter and easier to handle, making them ideal for applications such as railway drainage, where installation time is limited.
At Cotterill Civils, we supply a wide range of catchpits as well as inspection chambers. For expert advice, call our team on 0121 351 3230.
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