Catch basins and dry wells are two of many drainage solutions that keep water away from the foundation of your home. They’re both placed below ground, but they have significant differences.
A dry well is a large hole in the ground, usually lined on the sides with concrete or brick for reinforcement. They’re open on the bottom, although some may have a layer of gravel or stone for added filtration.
An underground pipe carries stormwater from roof runoff to the dry well, where it collects and seeps into the soil over time. Other setups use French drains to direct runoff along the natural drainage path to the dry well. Dry wells ease the burden on municipal storm drains, and some communities now require them.
Dry wells can also be used to recycle “gray water” from sinks, tubs, showers, dishwashers, and washing machines. The soil naturally filters the water it absorbs.
Dry wells should be placed in a low point of the yard, where the soil has a good infiltration rate, meaning that the ground absorbs water easily. Some soils, such as hard clay, aren’t suitable because the water could pool and take much longer to disappear into the ground.
Accumulation of debris can be a problem, causing a dry well to lose its ability to absorb water quickly and overflow. Dry wells should be covered with a grate for safety and to minimize debris collection. They should also have a mechanism to handle overflow from extreme rainfall events, such as an exit pipe that connects to a storm sewer.
A catch basin drain differs from a dry well in that it is fully enclosed. Water doesn’t drain out the bottom into the soil but exits via a pipe connecting to a storm sewer or other approved drainage area. Catch basins have grates on top to prevent them from collecting too much debris.
Sediment and debris that makes it past the grate of a catch basin sinks to the bottom and stays there while the water rises to the exit pipe.
Catch basins require regular cleaning to function properly and discourage pests. They can help reduce pollution from runoff if the sediment cleaned out of them is disposed of properly.
Although catch basins and dry wells are different, both must be installed with a proper slope leading to them so gravity will direct runoff toward them and away from the foundation of your home. These drainage systems collect water that might otherwise pool in low-lying areas or hardscapes on your property, such as patios. They keep water away from your home’s foundation, reducing water damage and seepage.