How to Replace a French Drain

Your French drain should end at the lowest part of your property.

French drains intercept water as it makes its way through your property, and redirect it along a specified path to a low point. Originally French drains were simple trenches with gravel. These days, most French drains also include a length or drainage pipe. If your French drain gets clogged or damaged, water may pool in the middle of your yard rather than draining. When this happens, simply replace the drain with a new one. The process is fairly similar to installing a new drain.

Things You'll Need

• Spade
• Shovel
• Tamper
• Measuring tape
• 4-inch PVC pipe
• Pipe collars
• Hacksaw
• Landscaping fabric
• Utility knife

Instructions

1. Place a spade into the ground over your French drain. Step down on the spade to cut the sod. Make a 1-foot square and remove the sod to expose the drain's gravel. Repeat this process for the entire length of the French drain. Place all of the removed sod pieces on the same side of the drain area.

2. Dig out the gravel covering your pipe. Place the gravel along the side of the trench opposite the sod. Continue digging further along the drain in the same manner until the entire pipe is exposed.

3. Pull up on the pipe to remove it from the ground. Discard the used pipe. Continue digging up the rest of the gravel that was under the pipe. Pile it alongside the trench.

4. Tamp down the bottom of the trench with a manual tamper so that the soil is even. Take care not to alter the angle of the trench bottom.

5. Shovel gravel back into the trench until you have built a 2-inch layer.

6. Measure the length of your trench. Connect sections of PVC pipe together with collars and elbows, so they will run the length of the trench. Cut the last section of pipe to fit if necessary,with a hacksaw. It is not necessary to glue the collars and elbows in place on this type of drainage pipe.

7. Wrap your PVC pipe in landscaping fabric, cutting the fabric with a utility knife as needed. Make sure the side of the pipe with the holes only has one layer of fabric over it. You don't need to secure the fabric.

8. Place the pipe into the trench with the perforations facing down. Fill the trench with the gravel that you removed earlier. Place the sod pieces you removed back on top of the French drain trench.

Tips & Warnings

• If your old French drain was having trouble moving water, it may have been caused by an improper angle on the bottom of the trench. Once you have removed the pipe and the gravel, use a level to check the slope of the trench bottom. A proper slope is 1 inch of drop for every 10 feet of trench. Adjust the slope as needed by moving dirt within the trench before installing your new piping.

• Not every French drain is covered by grass. If your drain is not, skip the steps pertaining to the sod.

References

• Ask the Builder: A Simple Trench Drain
• Grounds Maintenance: How to -- Install a French Drain
• Danny Lipford: Using a French Drain to Remove Standing Water in Your Yard
• Basement Troubleshooting Guide: Exterior French Drains