Do It Yourself Repair: Common Lawn Sprinkler System Problems

Many lawn sprinkler problems require a very simple fix, so there's no reason to pay someone else to do the job.

Most lawn irrigation system repairs take little time or know-how to fix. Furthermore, some three-quarters of these repairs can be considered common, being called for again and again. Translation: hiring a sprinkler repairman can be a big waste of money. This article discusses five common sprinkler system problems, teaching you why they happen and how you can fix them yourself. As with any lawn work, it's advised that you have your local power company locate your utilities before you dig.

Broken Heads: Sprinkler heads are often broken by lawnmower blades and snow shovels, or they sometimes break down after a long life. Often, the quickest way to fix a broken sprinkler is by unscrewing the stem from the canister and screwing a new stem in its place. If the sprinkler is indeed a lawnmower or snow shovel casualty, it's a good idea to dig a deeper hole for it to prevent the problem from happening again.

When digging up a sprinkler head, avoid prying on it with your shovel, because doing so might break the threaded connection underneath. You should also avoid jumping on your shovel blade or otherwise using excessive force, because you could accidentally slice through the pipe feeding the sprinkler. The best approach is to first cut a shallow, one-foot square into the sod around the head with your shovel. Then remove the sod by hand and stack it neatly to one side of the sprinkler. Using your hands or a small trowel, next remove the soil surrounding the head and place it on the other side. You'll want to dig your hole so that the top of head will sit approximately one-half inch above the soil. If the head is any deeper than this, it might pick up lawn debris that can damage its seal; if it's any higher, it might be struck again. Once you have the sprinkler at the proper depth, replace the soil an inch or two at a time, tamping it in with a small stick or the end of your shovel as you go. Solid tamping ensures that the head won't surface over time.

With the new head in the ground, it's now time to insert a nozzle in it. Determine what size nozzle you need by finding another sprinkler head on the same zone that waters a similar pattern (i.e., a full- or half circle) and match it. The information you need should be printed on the nozzle itself. Stationary spray head nozzles screw on top of the stem; rotor nozzles are held in place in the side of the stem with a setscrew. If the sprinkler you've just replaced is a stationary spray head, simply align your nozzle and call the job done. If the sprinkler is a rotor, you'll need to set its arc (how far the head turns during operation) and its radius (how far it sprays) before calling it quits. Look to your sprinkler head's instructions when making these adjustments.

Broken Pipe: Irrigation pipe can break for many reasons, either by freezing or downward pressure onto a sharp rock, or by the misplacement of a shovel blade or lawn aerator. Repairing a broken pipe is quick and easy, though, so there's no need to hire out this job. Before you can fix the pipe, you'll need to dig it up. As with digging up a head, use your shovel carefully and try to keep the sod neat so it can be replaced easily. And as you dig, try to feel for the pipe with your shovel so that you don't accidentally cut through it and create more work for yourself. Dig your hole big enough that you can work comfortably in it. Expose a foot of pipe on either end of the break, and remove three to four inches of dirt to either side and below the pipe.

The next step is to notice what type of pipe you're working with. Is it poly pipe, which is black or green and flexible? Or is it PVC, which is white and rigid? What size is it? If you can't tell, the best thing to do is to cut out a section of pipe, with either a hacksaw or pipe cutters, and take this sample to the irrigation supply store where you'll be getting the parts you need for the repair.

To fix a break in poly pipe, you'll need enough pipe to replace the broken section, two insert couplers, eight hose clamps, a screwdriver or socket set (for tightening the hose clamps), a hacksaw or pipe cutters, and a rubber mallet. First, cut away enough pipe so you have room for both couplers with some pipe in between. Second, using the mallet, lightly tap a coupler halfway into each end of the existing pipe and place four clamps on either end. Third, cut a section of pipe that is long enough to cover the exposed ends of each coupler and work it into place, being careful not to kink this new section of pipe. If the pipe wants to kink, you'll either have to cut the replacement section a bit shorter or expose a few inches of the existing pipe so it can flex more. Fourth, place two hose clamps on either side of each coupler and tighten them hand-tight. Be sure to check your work for leaks before backfilling your hole.

To fix a break in PVC, you'll also need enough pipe to replace the broken section, a slip-by-slip coupler, a slip-fix, some PVC glue and purple PVC primer. First, cut away enough pipe so that the coupler, new section of pipe and slip-fix (fully compressed) can all fit. Second, beginning with the coupler and then the slip-fix, apply first some primer and then some glue to each fitting and the first inch and a half of the existing pipe. Apply a good coat around the pipe and inside the fittings, twist the fittings half a turn as you slide them on, and hold the fittings in place for thirty seconds before letting go. Third, apply glue and primer to each fitting and the new pipe. Glue it first to the coupler and then to the slip-fix, and don't forget to twist them as you slide them on. Give your glue job a good fifteen minutes to cure before checking for leaks and burying it.

Stuck Valves: If a zone of sprinklers runs nonstop while your controller is off, you most likely have a stuck valve, meaning a small rock or other debris is preventing the valve from fully closing. That a valve can be stuck open is mainly a matter of design. Most small lawn irrigation valves have front and back sections that are separated by a thin rubber diaphragm when the valve is closed. Water flows only when an electrical current sent from the controller passes through the valve's solenoid and activates a mechanism that lifts the diaphragm. When the electrical current is broken and the diaphragm is dropped back down, the water stops. During this process, the diaphragm doesn't travel very far, so often a small rock will get pinched between the diaphragm and the valve's plastic framing, preventing a good seal. When this happens, water will flow through the valve continuously.

To fix a stuck valve, first try to take some pressure off the diaphragm by unscrewing the solenoid. After some water has passed through the valve, screw the solenoid back on. If the valve seals properly in the off position, the problem is solved. However, if the valve remains stuck open, you'll have to take the top off. Before dismantling the valve, turn the water to the system off so you don't get wet while working on it.

Depending on the make and model of your sprinkler valve, you may need a screwdriver or socket set to remove the connecting hardware holding the top on. Place any screws, nuts or bolts where you can keep track of them. Don't place them inside of your valve box, because they will likely become immersed in water when you remove the valve top. If you don't see any connecting hardware, you have a jar-top valve, meaning the top is designed to thread on and off by hand. To reduce strain on the wiring to a jar-top valve, it's a good idea to unscrew the solenoid before spinning the valve top off. Remove the top carefully, and take note of how things go together so you can reassemble the valve correctly later on.

Once you've removed the valve top, examine the valve casing and diaphragm for rocks or other debris and remove what you find. Debris in a valve can often be flushed out by turning the system water on for five seconds or (if the force of the water isn't enough) by removing individual particles with a small screwdriver or tweezers. Once the valve is clean, replace the top (and the solenoid if you removed it) and turn the system water back on. Your problem should be fixed.

If your problem is not fixed, however, and you didn't find any debris after removing the valve top, then that means the diaphragm is too worn to prevent flow and must be replaced. You can most likely find the replacement parts you need at an irrigation supply store. Make sure to write down the valve's manufacturer, any part numbers you find, and a brief description of the valve so the supplier has the information needed to help you.

Uneven Precipitation: If your lawn is lush and green in some areas, but crispy and brown in others, it's quite possible that your lawn is not being watered evenly. This could be caused by one of three things: one, the operation time for some zones is too low; or two, some heads have the wrong nozzle for the area they cover; or three, your heads are too far apart. To troubleshoot an uneven precipitation rate, first operate each zone manually and make sure the sprinklers reach head to head. If they don't reach each other, follow the manufacturer's instructions and try to adjust their radius (the distance they spray) and see if you can make them do so.

If you can get your heads to reach each other, you can probably save your lawn at little expense. The next step is to notice whether half-circle heads along the perimeter come on separately from full-circle heads in open areas. If so, doubling the run time for zones in open areas should solve your problem. Otherwise, you'll need to replace the nozzles in perimeter heads to ones that are half as large (i.e., from 2 G.P.M. to 1 G.P.M.), then double the run time to even out the precipitation rate for each zone.

If you can't get your heads don't reach any closer than halfway to each other, that's a strong indication that your heads are too far apart and you'll need more sprinklers to fix the problem, an expensive proposition at best. At this point, it's best to find out if your system is under warranty and, if so, have the installer rebuild the system correctly. If your system is not under warranty, you should consult an irrigation professional to determine the solution best for you. Until help arrives, you can minimize the effects of poor precipitation rates by increasing the operation time of sprinklers in drier areas.

Wiring Problems: If you can't get a sprinkler zone to come on from the controller, and you're confident the controller works well and has been properly programmed, bad wiring may be to blame. To troubleshoot your wiring, first check each connection for corrosion, and make sure the wire nuts are tight. Pay particular attention to the ground wire, because a solid ground is necessary for a valve solenoid to work. If you find corrosion, cut away the corroded section from each wire with a set of wire pliers, expose a small section of clean wire, and rewire the valve with a fresh wire nut. Once you've made sure all your connections are clean and tight, try again to operate the zone from the controller.

If things still aren't working, check for an unused strand of wire and, if you have one, wire it in place of the wire being used. If you don't have any extra wire, or rewiring the valve doesn't work, you'll need a fresh length of wire. You can trench the new wire into your lawn with your shovel by running your blade as deep as it will go, lifting up on the dirt, and tucking the wire into the groove by hand. Try to get your wire as deep into the ground as possible so that it has some protection, and walk over your trench to level out the sod when you're done. Use fresh wire nuts when rewiring your valves. For added protection, use "grease nuts," or wire nuts with caulking inside.

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