I like the flexible perforated pipe for drainage and leach beds rather than the perforated hard PVC pipe. The holes are smaller allowing only water in and evenly spaced in corrugated valleys to carry the water away.
I like the hard PVC pipe for non-perforated uses since it is easier to maintain the proper grade for flow through the pipe. However the non-perforated flexible pipe can work work well too.
To carry rainwater away from the house and avoid water seeping down basement walls and creating wet basement problems, use the Non-Perforated Pipe from downspout to storm drain inlet, street curb, or other disposal area. Or you can run it through a perforated pipe after it gets away from the house to leach into the ground.
Place an downspout adapter on the end of the downspout, and run non-perforated pipe to the disposal area. If a shallow line is needed from the downspout, a 90 Ell can be used. There are "TEE's", "Y's" and other fittings available for connecting two or more downspouts to the same line.
Basement window wells should be drained to prevent water from seeping down to the foundation wall and entering the basement.
The window well can be easily drained by running a line of non-perforated pipe from a drain in the bottom of the well to a disposal area. The use of flexibile pipemay be helpful in making grade changes and curves away from the well. 90 ells are available for extremely sharp curves. Using hard PVC pipe, you can use 90 ells and 45 degree connections to change the pipe's direction.
Wet basements are generally caused by ground water being either adjacent to or higher than the basement floor. To prevent the water from entering either the basement wall or at the footings, install perforated pipe in a gravel envelope completely around the house. The bottom of the line should be as low as the bottom of the wall or footing course BELOW the elevation of the floor, with a minimum slope. It should run to a storm sewer or other disposal area. Use 90 Ells to go around the corners. A "TEE" will tie together the ends of the foundation drain at the line leading to the disposal area.
For extremely wet areas or if you are extra cautious, fill the area inside the footer with crushed stone to a depth of 8 inches and have a hole for a pipe to pass through at one point in the footer. This will allow any water inside the footer to drain to the drain system outside the footer.
Use the perforated pipe installed in gravel to collect and carry water away. Drains like this installed up hill from the house can keep significant water from running down hill to the foundation, which in turn would have lead to a wet basement. In heavy clay soils, several lines of perforated pipe may be needed to speed drainage.
To carry water beneath your driveway, use non-perforated pipe in 10"-36" diameters. Crushed stone, gravel or compacted soil backfill material should be used as the bedding material around the culvert, with aggregate size not exceeding one inch. The minimum heights of cover for these installations are as listed in the table below.
Trench or Open Ditch Installations
Nominal Minimum Minimum Min. Trench
Diameter Thickness Cover Width
D B C W
10" 4" 12" 26"
12" 5" 12" 28"
15" 5" 12" 31"
18" 6" 12" 36"
24" 6" 12" 42"
30" 6" 12" 50"
36" 6" 12" 57"
Care during installation- Care should be taken to prevent damage to the pipe during the backfilling operation. Avoid dropping large clods or rocks directly on the pipe especially if the flexible pipe is being used. Impact loads of all types should be avoided until pipe is properly bedded.
Bedding- Pipe should be bedded in gravel. However, selected soil backfill material may also be used with satisfactory results, provided it is compacted. The bedding material should be placed around the pipe to a depth at least 2" over the top of the pipe. When selected soil bedding material from the trench excavation is used, choose small, loose particles of soil that will flow around the pipe and minimize soil setting. Avoid large rocks that may damage the pipe or large clods of soil that cause voids and subsequent excessive settling.
Depth of Cover- If vehicular traffic is expected over pipe, there should be a minimum of 12" of cover. Typical recommended gravel materials would be pea gravel, 6A stone, or pit-run coarse sand and gravel mixes.
Proper Grade- The grade, or fall, on which pipe is laid is critical in that reversals in grade will greatly reduce the effectiveness of the system. Best drainage results are achieved with a continuous downhill fall, or grade, over the entire length of the drain line. A fall of 0.2 inches per 10 feet of length is generally considered adequate. Greater fall will promote more rapid drainage. I like a fall of 1 inch for 10 feet of length, but that is not always possible.
Proper Selection of Materials- Choose your materials according to application. If absorption and drainage are required, perforated pipe should be used. If pipe serves only to move water away from an area (such as downspout run-offs, etc.), non-perforated pipe is best because it will not dissipate water into the surrounding area. Non-perforated pipe should also be used if the line runs close to trees where root penetration may be a problem. If the soil being drained is sandy or silty, then either a protective wrap, hay or gravel should be used to prevent the soils from entering and blocking the drainage line.