Why Does My Sprinkler System Have Low Water Pressure?

September 4, 2018

Low water pressure in your sprinkler system cuts down the irrigation range and can even cause the sprinkler heads not to pop up at all. Here are the most common issues:

  1. Valves on the backflow preventer device aren’t all the way open.
  2. The shut-off valve or main water valve isn’t all the way open.
  3. There is a leak or break in the water line.
  4. There is an obstruction in the water line.
  5. Sprinkler heads are dirty or clogged.
  6. There is increased demand on the municipal water supply.

Let’s take a closer look at each of these issues and how to diagnose and resolve them.

1. The valves on the backflow preventer device aren’t all the way open.

If your entire sprinkler system isn’t getting enough pressure but the water pressure inside your home is fine, your backflow preventer valves may not be open all the way. Fully open valves will provide the highest water pressure.

The backflow preventer device has two pipes: one horizontal and one vertical. Most have a valve on both pipes. The valves are fully open when the handle is parallel to the pipe. If you need to adjust the valves, turn the valve on the horizontal pipe first, then the vertical.

2. The shut-off valve or main water valve isn’t all the way open.

If there is a shut-off valve where your sprinkler system connects to your home’s water supply, check to ensure it’s fully open.

Did you recently need to shut off the main water supply? Check to make sure the valve is open all the way. A sprinkler system requires much more flow than your sink or shower, so you may not have immediately noticed that the valve was left partially closed.

If you have a municipal water supply, has there been any road work or pipe work in your neighborhood recently? Give your water company a call. It may be that the water was shut off on the municipal side and valve wasn’t fully opened again.

3. There is a leak or break in the water line.

Have you or a service provider done any digging in your yard recently? Have you put a garden stake, trellis, fence post, dog leash tether, or similar sharp object into the ground near a sprinkler line? If so, a water line may have been cut and will need to be repaired. Lines can also develop leaks.

To check for leaks and broken lines, look for depressions and abnormally wet areas in the lawn. When the sprinklers are running, you may see water bubbling up from the ground at the leak site. Also look for a series of sprinkler heads that aren’t working properly. A water line problem will be located between the last working head and the first non-working head.

4. There is an obstruction in the water line.

If you can isolate a problem area but there aren’t telltale signs of a leak, the water line may be obstructed. Is there a tree or large shrubs nearby? Roots can wrap around a water line and squeeze it closed over time. Are vehicles parked or do they frequently drive over the area? The weight may have compressed the soil and crushed the line.

In these cases, you need to replace the damaged section to restore water pressure. If tree roots caused the damage, reroute the water line.

Over time, small cracks can develop in the water lines and let in dirt. Dirt can also get into the lines during repairs and maintenance. It doesn’t take much dirt to form a clog, impeding water flow. The line will need to be flushed to the last sprinkler head of the affected zone, or repaired if there are cracked sections.

5. The sprinkler heads are dirty or clogged.

If the pressure is low at only one or two sprinkler heads, they may simply be dirty. Examine the sprinkler head and filter and clean if needed. Grass can also grow around the base of the sprinkler heads and cause them not to pop up fully, so trim and clear away any obstructions.

6. There is an issue with the municipal water supply.

Are your neighbors also experiencing low water pressure in their sprinkler systems? Has the weather been unusually hot and dry? Have you noticed that your water pressure drops at peak watering times, like in the early morning, but is better during other points of the day? Have there been new homes or businesses built in the area that could be drawing off the same water supply? Heightened demand on the municipal water system could be behind your low pressure issue.

Are repairs being made to pumps and pipes? This can cause water pressure to drop temporarily.

Contact your water company to find out if the water pressure in your area has dropped recently, and if so, how long it is expected to last. It may be a case of waiting until temporarily heightened demand goes down again. Your water company can recommend non-peak times to water your lawn when the pressure will be higher. If the drop in water pressure is permanent, you may need to reconfigure your sprinkler system to adapt to the lower pressure.

There are many potential causes of low water pressure in your sprinkler system. Many you can resolve on your own, but if you’re not sure, or the fix is more complex, it’s best to call in a pro. In the Wichita area, call Reddi Irrigation at (316) 858-0736 for friendly service.

Resources found on our website are provided as general guidelines, and Reddi Industries does not assume any liability resulting from the provided information.