What Is a Catch Basin? How to Install One in Your Yard
Catch Basins vs. Other Drainage Systems and Installation Tips
You never want water pooling around a home's foundation. Seepage, mold, wood rot, moss growth, insect activity, and long-term damage can occur. If runoff pooling is a problem for your home, then a catch basin drainage system might be a good option for you. It moves roof water runoff from the roof to an endpoint as far away from the house as possible, often near the property line.
Typically, roof water runoff collected by gutters is sent down a vertical downspout, and in most cases, gutter water can sufficiently find its way to a nearby sewer drain (if you live in a place with a sewer system). Some homeowners get plastic gutter extensions that move the water an additional 4 feet beyond the foundation. But extensions are not adequate if you live in a wet climate like Hawaii, the Pacific Northwest, Florida, and areas of the Northeast.
A catch basin is a buried container for receiving and redistributing surface water. The open top is covered with a slotted grate to allow water to pass through while blocking leaves and other debris. On the sides of the basin are holes for attaching pipes that move the water away from the basin.
How a Catch Basin Drainage System Works
A catch basin shuttles water away from your home through buried pipes to a spot safely away from your home. Here's a review of the start, middle, and endpoints:
- Roof: Rain or snow contacts the roof and runs down the gutters.
- Gutters: Gutters move the water horizontally to downspouts at one or both ends of the gutter.
- Downspout: Water from the gutters moves vertically downward through the downspouts.
- Catch basin grate: Water exits the bottom of the downspout and runs through the catch basin's top grate.
- Catch basin: Water rises in the catch basin until it reaches the exit pipe.
- Pipes: Buried 3-inch or 4-inch pipes running on a decline carry the water away.
- Exit Point: Water leaves the end of the drainage pipe, soaking into the ground or flowing away.
- Catch Basin Drains Off: Any remaining standing water slowly drips out tiny weep holes.
Pros and Cons of Catch Basins
Advantages of Catch Basins
- Prevents flooding
- Increases home value
- Inconspicuous while aiding landscaping
Disadvantages of Catch Basins
- Added cost to install
- Moist spot for insects, bacteria, and mold
- Can get clogged in a heavy rainstorm, causing pooling
- Can destabilize the ground integrity, causing a sinkhole
Catch Basins vs. Other Yard Drainage Systems
Drainage systems vary based on how much water needs to be transported and how the water is flowing. For example, a catch basin makes sense at the end of a water downspout. It catches the water from a fixed point. In contrast, a French drain can handle runoff water flowing across a wider area.
A French drain is made by digging a long trench and laying perforated pipe along the trench. Next, the pipe and trench are covered with rocks to filter out large debris, which still allows the water to percolate its way to the pipe. The water reaches the pipe and slowly seeps into the ground from the perforations along the bottom of the pipe. It is often installed on a decline to lead the water away from a home or spot that consistently has pooling.
If you live in an area with a lot of rainfall, like the Pacific Northwest, you can still install a French drain system; however, you might consider having an endpoint, like a catch basin. Heavy rain can overwhelm a French drain system, causing pooling.
A catch basin is sometimes used interchangeably to mean the same thing as a storm drain, but it is only a component in a storm drain. Both do the same thing by collecting the flow of excess water from rainfall. A storm drain is typically found along the sides of roads to deal exclusively with storm runoff, usually flowing to storm sewers.
A dry well is a large receptacle for unwanted water runoff. Water is collected in the well, either led there from a pipe or seepage from above. Over time, the water percolates through gravel or a porous, slowly seeping well wall, moving the water into the groundwater table.
Planning the Catch Basin Drainage System
Identify where the drainage system should start and end, including where you will place the catch basin. If the starting location is near a downspout, the catch basin will be located about 12 to 18 inches from the foundation, depending on the size of the catch basin.
The end of the run should be at least 10 feet away on a decline and farther for flat ground. Move the water as far away from the foundation as possible. The pipe should have a 0.25:10 decline or greater (1/4-inch per every 8 to 10 feet). If the pipe runs down a natural slope, you can likely dig the trench to a uniform depth. If there is no slope, create a trench running on a decline.
What You'll Need
Equipment / Tools
- 1 shovel
- 1 trenching shovel
- 8 string and stakes
- 1 hammer or mallet
- 1 caulking gun
- 1 electric drill
- 1 set drill bits
- 1 catch basin
- 3 PVC sewage pipes, 4-inch
- 3 bags drain gravel
- 2 packs plastic sheeting
- 1 tube silicone caulk
Building a Catch Basin Drainage System
Dig the Catch Basin Hole
Dig a hole for the catch basin to the depth of the basin, plus another 6 inches for gravel. Add the gravel.
Dig the Trench
Stake out the area to be trenched with the string and stakes. Then, use the trenching shovel to remove the turf and to dig the trench from the catch basin to the intended exit point. Toss the soil on a plastic sheet to avoid adding dirt and mud to the lawn.
Store Dirt Under Plastic Sheeting
Mound up the dirt from the trench under plastic sheeting. Close up the sheet at the end of every workday.
Run the Pipe Through the Trench
Once you have dug the trench to at least 8 inches deep, lay the 4-inch sewer pipe. Extend the pipe as far as you need.
When connecting the bell-end sewer pipe, the female end of the pipe (the bell) must be pointing up-grade; that is, in the direction of the catch basin.
Pour Gravel Around the Entry Point of the Basin
Concentrate much of the drain gravel under and around the catch basin. Also, have a gravel bed along the first foot or two along the drain pipe.
Push the Pipe Into the Side of the Basin
Other types of catch basins have a grooved ring. Gently twist the 4-inch pipe into the side of the catch basin and through the flexible sleeve. The end of the pipe sits in the grooved ring and is sealed with silicone caulk.
Pull the Pipe Into the Basin
On the inside of the catch basin, pull the pipe inward. Make sure that the pipe extends about 3 or 4 inches. Do not have the pipe enter the basin flush with the side of the basin.
Catch basins and pipes should be fitted tightly to be leak-free. However, some leakage is expected. This is not a pressurized system where no leakage is required. The PVC pipes do not need to be cemented.
Drill several weep holes at the bottom of the basin to prevent water from pooling.
Install a Pop-Up Emitter at the End
At the end of the pipe run, add at least 6 inches of gravel below the end of the pipe. Insert the pop-up emitter and its self-closing cap.
Build a Barrier Around the Drain Emitter
A barrier around the drain emitter is not mandatory but is helpful since it keeps the gravel in place and provides a barrier against lawn and weed growth. A simple barrier can be built from one-by-eight pressure-treated lumber to roughly 18 inches square. Cut a half-circle into one side (at the bottom) so the barrier can rest on the pipe.
Add Gravel Around the Emitter
Slowly pour gravel around the pop-up emitter to just below the level of the emitter's lip. Always keep the cap clear because frequent cleaning of the elbow joint is necessary.
Backfill the trench and around the catch basin with gravel, sand, or dirt. The more gravel you can use, the better. Gravel helps water drain away faster.
When to Call a Professional
Building a yard drainage system is not complex, but it does involve a lot of earth-moving. Professionals have trenching tools that speed up the process and eliminate much of the hard labor. For more than one or two runs of trenched drainage pipe, you may want to call a professional for help.
Rain and Precipitation. U.S. Geological Survey