What is a catch basin?

catch basin

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A catch basin is a variety of trap that prevents debris, sand, grit, and other contaminants from entering a drainage system. Catch basins can be found along the sides of roadways, in parking lots, along the edges of buildings, and in other low-lying areas. Smaller basins can be found as a part of a residential drainage system, and sometimes interior basins are used.

Water typically enters the catch basin through a grating at the top, an inflow pipe, or both. The water flowing into a basin arrives at a higher level than it exits, and the exit point is located well above the bottom of the basin. This design means that water carrying debris into the basin collects in the basin before leaving, and sediments from the water collect in the bottom of the basin.


Road side catch basin gratings are familiar to residents in Toronto and surrounding areas, where the storm sewer system is fed in part by runoff from the roadways. The City of Toronto makes efforts to ensure that residents pass nothing but rain and melted snow into roadside basins as those basins and sewers carry their water directly and untreated to rivers and lakes.


Basin maintenance

Catch basins require routine maintenance that includes clearing leaves and other debris from the grating as well as the occasional removal of accumulated sediments from the bottom of the basin. If a basin is backing up and the grating is not obstructed, then the outflow pipe might be blocked.

Gratings are cleared by simply removing the obstruction. Sediments accumulated in the bottom of a basin are often removed by large vacuum trucks that sometimes also have high-pressure water jets to dislodge harder to remove debris.


Catch basin repair

Catch basins are often expected to withstand rough treatment, as they might find themselves supporting parked vehicles and because they handle some of the less disciplined water flows. Although catch basins are usually built of a heavy concrete, they are still subject to frost heaving, cracking, and shifting. When these things happen, the seal between the grating and the concrete basin on which it sits can be broken and water can flow along the outside of the catch basin. This can quickly lead to crumbling asphalt and collapsed edges forming around the basin grating.

If a catch basin shifts on its foundation or if its pipes fail, water can flow outside the pipes and into the area surrounding the basin. As a consequence, a sinkhole can form. At this point more serious work needs to be done to repair the basin’s sewer connections and piping, and, if the basin itself is cracked or otherwise damaged, it may need to be entirely replaced. Such work also typically involves excavation, preparation and compaction of a new foundation, and concrete or asphalt work surrounding the grating.

catch basin sinkhole

Catch basin gratings need to be properly leveled and should be neither raised nor sunken into their surrounding paving. Failure to mount the grating properly on the basin, to level the grating properly in its surroundings, or to seat the basin firmly on its sub base can lead to improper drainage or water flow.

catch basin repair

You may be able to personally handle the lightest level of catch basin maintenance, but beyond clearing the grating further maintenance usually requires professional skill and equipment. Similarly, because catch basin repair can involve excavation, foundation compaction, concrete pouring, and asphalt work, basin repair is often the job of professionals. Contact Master Drain today if you are experiencing poor water flow through a basin or are seeing other signs of basin failure.

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