Catch Basin - Surface Drain Box for Stormwater Runoff
A catch basin is a surface drainage box with a grate that collects runoff and directs it into an underground storm drain system.
What It Is
A catch basin captures rainwater, driveway runoff, and other surface water before it can pond on pavement or flow toward a building. Water enters through a grated top and then drains through an outlet pipe, while heavier debris settles in the sump at the bottom.
That sump is important because it traps sediment, leaves, and trash that would otherwise clog the downstream piping. Regular cleaning keeps the basin working as intended.
Where It Is Used
Catch basins are used in driveways, parking areas, patios, low spots in landscaping, and at the base of exterior stairwells. They are part of stormwater drainage systems rather than sanitary sewer systems.
How to Identify One
A catch basin is usually visible as a square or round grate set flush with paving or grade. Below the grate is a box-like chamber deeper than the outlet pipe. Standing water, overflowing debris, or slow drainage during rain are signs it needs service.
Replacement
Replacement is needed when the basin body cracks, settles, loses slope to the outlet, or cannot be cleaned effectively because it is broken or collapsed. In many cases, the grate can be replaced separately from the basin body if the box remains sound.
Frequently Asked Questions
Catch Basin — FAQ
- What is the difference between a catch basin and a drain?
- A catch basin is a specific type of drain structure with a sump that collects debris before water enters the outlet pipe. A simple area drain may have a grate but no sediment-trapping chamber below.
- Why does my catch basin smell bad?
- Debris and standing water in the sump can create odor as organic matter breaks down. Cleaning the basin and restoring proper drainage usually solves the problem.
- How often should a catch basin be cleaned?
- Most residential catch basins should be checked at least before and after the rainy season and cleaned whenever debris buildup is visible. Trees, heavy sediment, or frequent runoff can require more frequent service.
- Can a clogged catch basin cause flooding?
- Yes. If the grate is blocked or the sump and outlet are packed with debris, stormwater has nowhere to go and can overflow across the yard, driveway, or toward the foundation.
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