You might find yourself double-checking your sprinkler schedule if you find that one head or zone that appears to be running when the system is supposed to be off. If the system really should be off, you have a leak on your hands.

There are two main reasons a sprinkler system can leak when it’s off: improper grading and a leaking valve. Here’s how to identify and fix these problems. Plus, we’ll discuss a problem that only makes it look like your system is leaking while it’s turned off.

The Grading of Your Sprinkler System

One reason a sprinkler system may leak when it is turned off is that the grading of your ground or system places one sprinkler head deeper than the others. The water from the rest of the line then runs down towards that sprinkler head and leaks out the top. If this is your problem, the sprinkler head will leak every time the system is turned off. However, it will stop a few minutes later after all of the water is released (because no new water is added to the system).

The simplest solution to this problem is to install check valves after each sprinkler head. Check valves stop the flow of water in the lines, so that it can’t reach the lower sprinkler head. Alternatively, you could fix the grading, but that is significantly more expensive and disruptive to your yard. However, if you are already making changes to your sprinkler system, it may be worthwhile to raise the lowered head while the ground is already open.

Leaking Sprinkler Valve

The second reason that a sprinkler system could leak when off is that the valve for the whole zone is leaking and allowing new water into the system. This type of leak creates a steady, small trickle that does not stop. The leak may be at one or more of the sprinkler heads in the zone. Or, the leak could pour out a line if there is a crack or hole in it. These leaks are more serious than the grading problem because they can waste a lot of water and can go undetected. Over time, the valve is likely to allow more and more water into the system.

Thankfully, the solution is simple. Have a professional repair or replace the valve. In most cases, replacement is a wiser idea. It’s also a wise idea to have your professional look at the valves for the other zones, as they may also have suffered damage as the first one did.

Your Landscaping Has Poor Drainage

If water is sticking around more than it normally does, it may seem like the system is leaking when it’s off. That could be the case, but it could also just mean that a change on the property has reduced its drainage. New retaining walls, major soil replacements, and other landscape changes can create poor drainage. You should always have a sprinkler system expert reconfigure your sprinklers to account for these changes and keep water draining properly.

Don’t ignore signs of poor draining or of sprinkler system leaks. Not only will both problems waste your water, but they can also damage your yard and landscaping.