A dry well provides an excellent means of drainage for both gutters and low points in your yard. Water collects inside the cavity and drains gradually into the soil in the area. There is no reason why, with a little effort, you can't install one of these on your own.
Step 1 - Select the Type You Need
The type of dry well you should have is affected by how much water you expect to collect. Small amounts of water can be collected in a space filled with loose stones and gravel, but if you get heavy storms on a regular basis, choose a plastic or concrete dry well. These will essentially be a shell with holes. Water will come in through the holes and fill the open space inside. This larger well can take more water than a simple trench filled with rocks.
Step 2 - Find Your Location
Choose the location for your dry well. A natural low point in the lawn makes the most sense, otherwise you have to create one. Remember, all water must flow down a slope to reach the dry well.
Step 3 - Dig
Dig sloping trenches first for pipes leading from drains and gutters to the dry well. Trenches should be deep enough to allow six inches of soil above the pipe, and they should slope at least 1/4-inch for each foot of pipe. The dry well itself should be set deep enough for these pipes to enter near the top of the open space. You also need to open a space large enough to hold the water you expect to your dry well, then a little extra so you have space to place everything.
Step 4 - Lay PVC Pipe
Install PVC pipes in the trenches, cut to the length you need the water to travel. The perforated sections of pipe should be close to the dry well, allowing water to percolate on its way to the storage. Wrap these sections of pipe with landscape fabric. This will keep soil from entering the pipe and clogging it. Then, surround the perforated pipe with gravel to improve water travel around it.
Step 5 - Fill the Dry Well
Fill the bottom of the dry well pit with stones and gravel. This will allow the water to flow out and into the soil, slowly, as it is supposed to. If your well capacity is small, fill the entire space with gravel and rocks after lining the sides with landscape fabric to keep soil from filtering between the rocks and filling the space left for water.
If you need a larger capacity well, install the plastic or concrete shell over the layer of stones and gravel and hook up the PVC pipes. Wrap the dry well with landscape fabric to keep loose soil from flowing in with the water and eventually filling the space.
Step 6 - Cover
Pack gravel in around the sides of the dry well or backfill the area with soil. If you backfill, it is imperative that you remember the landscape fabric. Leave a drain opening connecting the top of the dry well area to the soil, allowing the passage of air in and out of the space. Then, backfill the pipe trenches.