How to Repair a Broken Black Plastic Main Water Line

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Things You'll Need

  • Hacksaw or reciprocating saw

  • Utility knife

  • HDPE coupler

  • Water or mineral spirits

  • Rag

A cracked black plastic HDPE (high-density polyethylene) water main can create serious water damage in or around your home. The quicker you get to the cracked line and repair it, the less water will soak into your walls or floor. Fortunately, as long as you can easily access the water line, the fix is relatively straightforward and easy to complete.


Step 1

Locate the main water shut-off valve and turn off the water to the entire building. This will eliminate water leaking from the break in the water line. In most cases, you will locate the shut-off valve where the waterline enters the home. Usually this is in the basement.

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Step 2

Remove any standing water from the area where the crack in the pipe is located. For most in-home repairs, this is easy. However, if the crack happens to be outside and buried under ground, you must remove the water with a bucket or pump.

Step 3

Cut the section of cracked pipe from the HDPE tubing with a hacksaw or reciprocating saw. Remove the burred plastic left around the edge of the pipe with a utility knife. Burring happens when you cut the plastic with a saw. You can deburr it by running the sharp edge of the knife around the inside and outside edges of the pipe


Step 4

Measure the gap left in the pipe with a tape measure. Then, measure the diameter of the pipe by measuring across the face of the cut pipe with your tape measure. Purchase a HDPE coupler that fits these measurements. There are many kinds of couplers on the market. Purchase a coupler designed for a watertight fit.


Step 5

Clean the inside and the outside of the pipe near the ends where you will attach the coupler. You can use water and a rag or you can use mineral spirits and a rag. Mineral spirits will remove any grease found on the plastic surface.

Step 6

Connect the coupler to one end of the pipe. In some cases, you do this simply by pressing the pipe into the coupler. In other cases, you must slide the pipe into the coupler and then turn the coupler with a pair of pliers to tighten it around the pipe. Follow the directions supplied with the specific coupler you purchase.


Step 7

Lift up on the couple and then lift up on the second piece of pipe. Slide the pipe into the coupler and secure it in the same manner as you secured the coupler to the other piece of pipe.


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