How to Repair a Buried Sprinkler Pipe
Just like many problems in life, there is more than one way to fix a broken sprinkler pipe. The appropriate method depends on the damaged section's location. For instance, a clean break before the valve usually requires a hard pipe repair, while easier repair methods work fine when the damaged area occurs after the valve.
This guide will break down five different methods to repair a buried sprinkler pipe.
Locate and Expose the Damaged Pipe
Finding the leak sometimes becomes the most difficult part of this project. Obviously some leaks are easier to find than others, such as a geyser that rips through the soil. In less obvious cases a homeowner may only notice a pressure loss at the end of a zone. In this situation, turn on the leaking zone. Stand back and compare the spray height of each sprinkler head. If you see a loss in water pressure between two sprinkler heads, suspect a leak between these two heads. Go to the suspected area and look for overly saturated soil.
Remove the soil covering the broken sprinkler pipe with a shovel. When the tool's blade touches something hard, stop digging with the shovel and expose about a two foot long section of the pipe with either a hand or small trowel. Clear a 4- to 6-inch deep trench under the sprinkler line. This gives the water inside the pipe a place to drain.
Identify the pipe size before shopping for repair fittings. The person at the hardware store does not know what size pipe you have. Manufacturers print the pipe size on the side of the pipe. Unfortunately this is often hard to read when on older buried pipe. In this case, wrap a piece of string around the pipe and make a mark where the end meets. Go the hardware store and use the string to identify the pipe size. If you feel the need to gamble on pipe size, choose 3/4 inch.
Saddle Repair Kit
Irrigation repair technicians use a saddle repair kit to fix a cracked section of straight pipe, such as when someone punctures a sprinkler pipe with a shovel. The pieces in these kits hug pipe, not fittings; leaking fittings require a hard pipe repair. Some kits use a PVC saddle and cement, while others use a rubber gasket and metal clamps.
PVC Saddle style
- Wipe the damaged area with a rag to remove mud and dry it. If water continues to seep from the break, turn off the water source and remove the closest sprinkler head. This releases the water pressure from the pipe.
- Paint the pipe with a PVC cleaner or primer. Using a PVC cleaner or primer helps ensure the repair kit bonds permanently onto the pipe.
- Apply a liberal amount of cement to both the pipe and the repair kit.
- Position the kit's pieces over the damaged area and snap them together. Let the cement dry, using the time recommended by kit manufacturer as a guide, before leak testing.
- Clean the surface of the damaged pipe with a rag. Remove all dirt and debris.
- Slip the clamp over the damaged area of the pipe. Position the clamp's rubber gasket over the damaged area.
- Assemble the clamp. Tighten the clamp's bolts with the correct sized wrench. Turn on the water source to check for leaks.
Many homeowners love the trees in their yard. Unfortunately as the roots grow they push up on any irrigation pipes running above them. Eventually the tension causes the pipe to crack and leak. The root's upward force creates uneven pipes that sit at odd angles to each other, making a hard pipe repair difficult. To make matters worse, removing the offending root can damage or kill the tree. A flexible coupling solves this issue without cutting the roots.
- Lay the flexible coupling on the damaged pipe and center it over the split in the pipe. Use the coupling to determine where to cut the pipe and mark the pipe with a pencil at the appropriate spots.
- Cut pipe on the pencil marks with PVC cutters. Remove any burrs with a knife.
- Let the water drain from the pipe. Dry and clean both ends of pipe with a rag.
- Apply a liberal amount of wet-or-dry PVC cement to the both ends of the flexible coupling and the sprinkler pipe. Quickly move to the next step.
- Slip both ends of the coupling over their respective pipe ends. Twist the coupling back and forth about 1/4 to 1/2 turn. Let the cement dry, using the manufacturer's instructions as a guide, then leak test the repair.
Irrigation repair technicians looking for a no-glue fitting often choose to use a PVC compression coupling, sometimes called a dresser coupling. A PVC compression fitting uses rubber gaskets as a mechanical sealant. When the technician tightens the fitting's nuts the nuts force the rubber rings into the void between the pipe's outer surface and the fitting. If the fitting leaks, the technician simple tightens the nut another half turn. Unfortunately a PVC dresser fitting should not be used on a constant pressure pipe, such as the pipe feeding the valve. In that case, pick a different repair method.
- Remove about 2 inches of pipe. This cut does not need to be exact, just close.
- Slide both dresser nuts over their respective ends of the pipe.
- Work both rubber bushings onto their respective pipe ends. Push one rubber bushing about 5 inches away from the cut end of the pipe. Position the second rubber bushing about 1 inch from the end of its pipe.
- Slip one end of the dresser coupling over the pipe with the bushing placed five inches from the end. Continue to adjust the fitting until the free end clears the remaining pipe.
- Position the end of the compression fitting against the rubber bushing that sits 1 inch away from the pipe. This should center the coupling over the two-inch gap.
- Slide the distant bushing toward the coupling until it touches the fitting. Both rubber bushings should now touch the fitting. Tighten both nuts with a wrench.
- Turn the water pressure on and leak test. If the fitting leaks, place one wrench on the coupling and a second on the leaking nut. Hold the coupling still and turn the nut approximately one half turn. Repeat as necessary.
An expanding coupling, sometimes called a telescopic coupling, works well when replacing a leaking fitting located in a tight space, such as inside a valve box. The stationary end of this fitting attaches directly to a section of pipe and the fitting's movable shaft slides into another pipe fitting. Occasionally a repair technician completes a hard-pipe repair with an expandable coupling; however, this situation rarely happens due to the fitting's high cost.
- Fully expand the coupling and measure its length. Subtract two inches from the measurement and transfer the calculation to the leaking sprinkler pipe.
- Cut the sprinkler line at the appropriate spot with PVC cutters. Let the water draining from the pipe absorb into the ground before continuing.
- Wipe the PVC pipe in the repair area with a dry rag. Removing all the dirt and debris from the pipe helps ensure a leak-free connection.
- Attach a PVC fitting to the end of the pipe that accepts the expanding coupling's shaft. The type of fitting depends on the repair. If the shaft connects to a threaded valve port, coat a male fitting's threads with thread tape before installing it on the valve. If the shaft slides into a coupling or other fitting, apply PVC cement to both the pipe and fitting. Install the fitting on the pipe, using a twisting motion.
- Fully compress the expanding coupling.
- Apply cement to both the PVC pipe and the expandable fitting's coupling end.
- Mount the expanding coupling onto the pipe, using a twisting motion. The twisting motion blends the cement.
- Cover the shaft's mating end and its fitting with PVC cement. Quickly slide the shaft into the fitting. Rotate the shaft back and forth slightly. Follow the cement manufacturer's recommended curing time before leak testing.
Hard Pipe Bridge
Occasionally it makes sense to build a hard pipe bridge using PVC pipe and fittings, such as when a sprinkler line passes over multiple growing tree roots or when the leak is located in an area too small for other methods. The exact type and amount of fittings needed depends on the situation, however, most pipe bridges use four 90-degree fittings and a section of pipe.
- Dig a ditch across the entire repair area. This exposes all obstacles.
- Cut the pipe on both ends of the repair with PVC cutters. Let the water drain from the pipe and soak into the soil. Dry and clean the pipe ends with a dry rag.
- Attach a 90-degree fitting to one buried sprinkler pipe with PVC cement. Turn the fitting until its open port faces up. Repeat this on the other buried pipe. Both 90-degree fittings must face the same direction.
- Cut two risers from a length of PVC pipe. The length of the risers depends on the amount of height needed to clear the obstacle. It sometimes helps to lay a scrap piece of pipe on the obstacle in the trench and measure the distance from the bottom of the scrap to the top of the buried pipe. Try to keep the risers as small as possible. Cement a 90-degree fitting onto each riser.
- Measure the length of the removed section of pipe. Transfer this measurement to a new piece of pipe and cut at the appropriate spot.
- Attach one of the 90-degree fitting on one riser to the new pipe with PVC cement. Cement the 90-degree fitting on the remaining riser to the pipe's other end. Twist the 90-degree fitting until the second riser's position matches the first.
- Apply a liberal amount of PVC cement to both of the 90-degree fittings connected to the buried sprinkler pipe. Position the bridge in the trench and slip a riser into each buried fitting. Press the risers into their respective fittings. Let the cement cure completely before leak testing.
This article is accurate and true to the best of the author’s knowledge. Content is for informational or entertainment purposes only and does not substitute for personal counsel or professional advice in business, financial, legal, or technical matters.
© 2019 Bert Holopaw