How to Seal an Underground PVC Pipe From the Inside

Turn off the water source that supplies the PVC pipe you are working with. Dig down to the piping with a shovel. Be careful not to hit the piping with the shovel, otherwise you may have an even bigger sealing job on your hands.

Use a PVC cutter or hacksaw to gain access to the inside of the pipe. Find the damage you want to seal and cut a few inches on each side of the surrounding area.

Clean the inside the pipe area you are working on with a washcloth. Sand the surface lightly with medium-grit sandpaper to give the putty a better surface to adhere to.

Put rubber gloves on and cut small, equal parts of your epoxy putty. Roll them together like a snake and then fold the combined mass in half. Then roll the putty into a ball. Repeat this rolling process until the putty is a uniform color.

Press the putty into the area that you want to seal on the inside of your PVC pipe. The putty will mold well to the contours of the pipe. Most epoxy putty will cure within 30 to 60 minutes after mixing unless it is a quick-dry formula, which may take only 5 to 10 minutes to cure. Read the product instructions thoroughly before using.

Use PVC couplers/fittings to rejoin the areas of PVC piping where you cut it. Apply a thin coat of PVC primer to the ends of the piping and then directly apply a thin coating of PVC cement on top of the primer. Push the ends of the piping into each end of the coupler/fitting to connect the two sections.

Look on the PVC cement package instructions for recommended drying time. Turn the water source back on after that amount of time has passed. The putty will cure underwater; there's no need to worry about this aspect of the project.

Recover the piping with dirt. Clean tools and any surfaces used immediately after you are done with the project. Use soap and warm water for this.