When it's installed correctly, a perforated drainage pipe is an effective solution to problems with standing water or excessive ground water near a building's foundation. Drainage pipes are commonly used to move rainwater from gutters away from a house or to drain wet areas in low spots of the yard. A perforated pipe may also be used near the base of the home's foundation footers as a drain tile; in this case, the drainage pipe is usually connected to a sump pump. Proper slope of the perforated drainage pipe is important for optimal drainage.
Dig a trench roughly twice the width of the drainage pipe and at least 2-feet deep with a shovel. Cut out roots as needed so the pipe can be placed straight, or only slightly curved, in the trench.
Use a small sledgehammer to install stakes every four feet along the trench.
Tie a string to the stake at the location where the water will enter the perforated drainage pipe.
Tie the string to the next stake in the trench. Use a line level to level the string between the stakes. Move the string down on the second stake ½ inch or more to create a minimum slope of 1/8 inch per foot of linear run. Repeat for each consecutive stake in the trench.
Use a tape measure to measure the distance from the string to the bottom of the trench, starting from the beginning of the trench, and add or remove soil as needed to maintain a consistent distance from the string the entire length of the trench.
Use a tamper to compact the soil between the stakes. Check the distance from the bottom of the trench to the string after replacing soil and compacting with the tamper and adjust as needed to maintain the correct distance.
Remove the string and pull out the stakes.
Place landscaping fabric in the trench to prevent soil from entering the gravel around the perforated pipe. Extend the fabric up both sides of the trench and out onto the ground surface; you will use the excess to cover the trench's gravel infill.
Add 2 inches of gravel to the base of the trench and smooth it with a garden rake, maintaining the slope of the bottom of the trench.
Place the perforated pipe in the trench with the holes facing down.
Fill the trench with gravel to within 4 to 6 inches of the soil line.
Wrap the edges of the landscape fabric over the top of the gravel.
Replace the soil and sod on top of the landscape fabric.