Black poly pipe (polyethylene or PE pipe) is used in many facets of home plumbing, both for drinking water lines and other applications inside a residential house. This type of pipe is available in very long rolls for the water main between the meter and the house and for sprinkler systems. Similar to PEX pipe, black poly pipe is made from polyethylene and known for durability. However, like other types of plumbing pipes, it does not last forever.
Black poly pipe can develop leaks with time and with the help of tree roots. As roots grow, they push against the pipe and eventually break it. Poly pipe also can be damaged by rocks in the soil that may shift and apply pressure to the pipe.
Before Getting Started
Black poly pipe repair can be difficult if it is installed deep in the ground and the hole is not big enough to allow for plenty of pipe movement. Locating the source of the leak can also be difficult. Sometimes you will be able to locate the problem by digging up the wet area in your yard. However, you may not always get so lucky and the wet spot will be a long way from the actual leak if the water follows a gopher hole or other type of cavity. Either way, expect to do a fair amount of digging.
Call Before You Dig
Be sure to call 8-1-1, the national call center of the "Call Before You Dig" program. The center will notify all utility companies with service lines on your property. The companies will send someone out to mark their lines, which may take up to three days but usually is free-of-charge. You must have your lines marked before digging in your yard, to prevent accidental contact with, or damage to, utility lines, including electrical, gas, water, and cable lines.
Black Poly Pipe Sizes and Fittings
Black poly pipe comes in a very wide variety of sizes. Common household pipe sizes often range between 3/4 inch and 2 inches, but these pipes can also be measured in millimeters between 16 mm and 1,000 mm for specific projects and industrial purposes.
Fittings for black poly pipe are not made from polyethylene for most applications, but there are several options to choose from based on your project and needs. These pipe fittings can be made from PVC, brass, or steel:
- Elbow fittings can turn poly pipe at 45- or 90-degree angles.
- Couplings are fittings that attach two pieces of poly pipe of the same size in a straight line.
- Reducer and adapter fittings can join two different ends of poly pipe together. Use reducers for pipes of different sizes, and use insert adapters for changing male and female ends of poly pipes for your project.
- Tee fittings add a new connection to your pipe. These are available in T-shaped fittings that add one new connection (most common) or special three-way fittings that can add multiple new pipes.
Equipment / Tools
- Trenching-style shovel
- Wood shears (optional)
- Pipe cutter
- Handheld torch (optional)
- Pinch clamp tool (or similar)
- Brass barb couplings
- Hose clamps
- Hot tap water (optional)
- Liquid soap (optional)
How to Fix a Black Poly Pipe
The standard repair for a black PE pipe is to install one or more brass barbed couplings secured with hose clamps. You will need to use specific clamps (ones used to secure pipe to fittings) and a tool that squeezes the clamp around the pipe securely. It is good practice to double up on the clamp on each joint for extra strength at the connection.
It's best to use couplings with a nut portion in the center to identify that the fittings are brass, which is required in many areas. If the damaged portion of pipe is large, you will need two fittings and a new section of PE pipe to make a spliced connection. Be sure to follow all local code requirements for the repair.
If the pipe you are repairing carries potable water, you may need to use different connections and fittings. Check your local codes to ensure you're using the proper tools and materials.
Shut the Water Off
You don’t want to be bailing water while you are trying to dig. You can always turn the water on if you think you are getting close to the leak. Or, turn the water on once the pipe is exposed to see exactly where the leak is located.
Unless you know how deep the pipe is located, you should dig carefully so that you don’t end up hitting the pipe. If you know about how deep it is, you can dig the first bit quickly until you get closer. Otherwise, dig slowly. As you get close to the right depth, switch to a smaller trenching-style shovel for more control. Make sure to expose all the way around and under the pipe to make it easy for you to work. Also, cut back any roots and remove any rocks that may damage the water line now or in the future.
Plan the Cut
First double-check the location of the leak. It’s important to pinpoint where the leak actually is so that you can decide what fittings you’ll use for the repair. If the leak is at a tee, you may be able to loosen the clamps and remove the barbed tee from the pipe so that only one pipe has to be cut. Since you may have only a little room to work with, you want to avoid shortening the pipe on more than one side of a fitting, if possible. Decide how best to cut the pipe to make the repair based on where it is located. Then use a pipe cutter to cut the pipe.
Install the Fittings
Put the pipe clamps onto the pipe before inserting the each barbed fitting into the pipe. Insert one end of the fitting into the pipe, pushing it in as far as it will go. It can help to heat up the pipe by dipping it in a bowl of very hot tap water (not boiling water) or use a little liquid soap to lubricate the barbs if you have trouble pushing the fitting in.
If you're still having trouble pushing the fitting in, you can try using a small handheld torch (if you have one) to heat the pipe. Heat it quickly by waving the flame over the first four inches of pipe, then try pushing the fitting in—it should be much easier now.
Lift both ends of the pipe, line up the other end of the fitting to the opposite pipe and push the fitting into the pipe as you push the pipe down.
Tighten the Clamps
Slide the hose clamps up so they are positioned over the barbs. Tighten each of the hose clamps with a screwdriver, using the pinch clamp tool if necessary. Make sure the clamps are secure and don’t move around.
Check for Leaks
Turn the water on to check for leaks before backfilling over the pipe. Sometimes the clamps will need a little extra tightening, so give them plenty of time to be sure they aren’t going to leak before you cover them up. Once you are certain nothing is leaking, backfill the dirt, being careful to pack the dirt down around the pipe as you go to prevent disturbing the fittings.
How long does poly pipe last?
High-density polyethylene pipe (also referred to as HDPE pipe or PE) typically lasts at least 50 years before needing repair, but some pipes can last up to 100 years.
What is the best type of pipe to use for an underground water line?
Underground water lines are commonly made from polyethylene, PVC, and PEX.
Can you use PEX fittings on black poly pipe?
PEX fittings can be used on polyethylene when barbed insert fittings are used, sometimes requiring clamps. PVC, brass, and steel fittings are the most popular choices for attaching black poly pipes together.