How to Drain Standing Water With a Dry Well

Dry wells can range in size and complexity from a simple sock filled with gravel, to drainage pipe fed concrete structures with a capacity of hundreds of gallons. A dry well is an underground container that receives drain water and leaches it into the surrounding soil. It has holes in it that are covered with screen to prevent dirt from getting inside it. It's usually made of plastic or concrete and is located directly under the wet area or far from it in better draining soil.

1. Evaluate the soil. Find out why it's not draining. Does it have a sub-surface layer of hardpan? Does you soil contain a large percentage of clay? If you have any of these problems, you will have to dig past the obstructions or locate farther away to get adequate dry well drainage.

2. Do a percolation test to see how fast your soil drains where you will be putting the dry well. A simple way to do this is to: dig a 4" hole with an auger to the depth of about 4 feet fill the hole with water and let it soak in really well. Do this a couple of times. Place a styrofoam ball at the end of a ¼ inch dowel. Fill the hole with water again and lower the dowel with the ball into it. Support it at the top with a couple of eye screws and measure the amount of rod out of the hole. Measure the level every 5 minutes to determine how well the soil is draining water. If it takes a day or more to drain, you will have to dig elsewhere or go deeper with your well. If it take 10 minutes or less to drain, you may have found the right location.

3. Size-up the Need. Determine what size dry well you will need for your application. How many gallons of water do you need to drain?

4. Get Permits

5. Before you dig, make sure you contact your city or county to determine if any cables or gas pipes are buried under your shovel. Some municipalities will also require you get a building permit for the larger dry wells. It's wise to ask first before you start your project.

6. Small Puddle

7. Once your planning stage is over and you have decided on the size of well, you can start digging. If your problem is just a consistent puddle, your dry well does not have to be complicated.
   Dig a 6" diameter hole with an auger or post hole digger, to a depth of 4 feet.
   Get a 4" drain pipe sleeve, tie a knot on one end and fill it with 6" of pea gravel.
   Lower the sleeve into the hole and continue filling with pea gravel until full. The sleeve will stretch and fill the 6" diameter hole.
   When it's full, tie a knot on the end and cover the whole thing with sandy soil.
   If this does not provide enough drainage, drill another hole and do it again until your puddle drains to your satisfaction. If you still are not getting enough drainage, then you will have to use a drainage pipe.

8. Perimeter Drainage.

9. If you have a larger problem or if your house has no rain gutters and you have a leaky basement, you will have to install drainage pipe from the wet area to a dry well. Dig a trench 12 to 14 inches deep around your house's perimeter or where you need drainage.

10. Insert 4" drainage pipe (pipe with holes or slits in it) into a drain pipe sleeve long enough to cover all the pipe.

11. Lay the sleeved pipe into the trench and cover with gravel to 4" from the surface. Fill the remaining 4" with well draining top soil or mulch.

12. Connect the end of the drainage pipe to the dry well with regular 4" PVC pipe.

13. Large Dry Wells

14. Locate an area with good soil percolation. When you have a large area to drain, you will need a larger dry well system. You can get several 50 gallon plastic dry well kits and connect them together or install a 1,000 gallon concrete dry well with a leaching field if necessary.

15. Dig a pit that's at least twice the depth and diameter of the dry well. If your soil percolates slowly, you will need to make it even larger.

16. Cover the bottom of the pit with 2 feet of gravel and place the dry well in the middle and about 2 feet below the grade surface.

17. Fill a two foot area (or more if poor percolation) around the well with coarse gravel.

18. Cover the entire pit with building paper and fill with two or more feet of topsoil.

19. A dry well is a project that is within the scope of the do-it-yourself home owner. If your project is huge, you will do well to hire a backhoe operator and have the dry well delivered and placed into the pit. Remember that it's better to overestimate the size of the dry well than to have to install a second well.