Common Causes of Low Sprinkler Water Pressure and How to Fix Them

Updated on Sept. 15, 2025

In order to have a vibrant and healthy yard, it’s vital that your sprinkler system works properly. While there are many things that can go wrong with a sprinkler system, one of the leading problems involves low water pressure. When the water pressure is too low, the sprinkler system will not function correctly. If this issue occurs, it’s best to have a professional sprinkler repair company come to address it promptly.

We’ll talk about some of the most common reasons for low-pressure sprinklers in this post.

How Water Pressure Works in Sprinkler Systems

Before we get into the reasons, it’s helpful to know how water pressure works in a sprinkler system. PSI, or pounds per square inch, is a unit of pressure. Most spray heads need between 15 and 30 PSI to work right, and most rotor heads need between 30 and 50 PSI. Most of the time, drip irrigation works at even lower pressures, usually between 10 and 25 PSI.

If the PSI drops below the recommended range, the sprinkler heads may sputter, the coverage may become uneven, and your lawn may get dry patches. Too much pressure can also be a problem, causing misting and wasted water.

Table of Contents

Backflow Preventer Valve Issue
Shut-Off or Main Water Valves Aren’t Fully Open
Clogged or Dirty Sprinkler Heads
Water Line Obstruction
Other Common Causes of Low Sprinkler Pressure
How to Test for Low Water Pressure
Fixes and Upgrades
Preventive Maintenance Tips

Backflow Preventer Valve Issue

One of the leading reasons for low sprinkler water pressure relates to the valves on your backflow preventer device. If you notice limited water pressure in your sprinkler system but normal water pressure inside your home, then the problem might be that your backflow preventer valves are not completely open.

If this is the only issue, the fix is simple: access your backflow valves and open them completely to improve your water pressure. Most backflow preventer devices have two pipes: one that is horizontal and one that is vertical. Since there is typically a valve on both pipes, we’ll make sure that all valves are fully open.

The valves are open once they are parallel to the pipe. We make sure to make adjustments to the horizontal pipe first before moving onto the vertical pipe. To ensure that this is done correctly and that it is the only cause for concern with your sprinklers, it is best to have a professional handle this process.

Water Line Leak or Break

A much more concerning problem involves a break or leak in your water line. This issue is typically caused by digging too close to a water line, then accidentally breaking it. This is common when homeowners install garden stakes or fence posts and accidentally damage one of these lines.

If this is the case for your home, then you should call a sprinkler repair technician immediately and always make sure you know how to find sprinkler lines before digging.

A sign that you have a broken line or leak is if you notice any depressions or abnormally wet areas on your lawn. Another sign is if you see water bubbling, which could indicate where the leak is located. One other sign to look out for is a series of sprinkler heads that aren’t working correctly. This could also indicate where the leak is located.

To ensure that the problem is detected and fixed properly, it’s highly recommended that you call the professionals at Andy’s Sprinkler to handle the whole process.

Shut-Off or Main Water Valves Aren’t Fully Open

Other valves you have to keep in mind include the shut-off valve and main water valve. Sprinkler systems typically have a shut-off valve that connects to your home’s water supply. To ensure adequate water pressure, be sure that this valve is opened all the way.

You’ll also want to keep in mind your main water valve, which is the valve that provides water for your entire home. To ensure proper water pressure, make sure that this valve is completely open as well. To help find these valves and ensure they are fully open, contact a professional for assistance.

Clogged or Dirty Sprinkler Heads

Sometimes sprinklers can show that there is a problem with the water pressure, but other times the problem is with the sprinkler head itself. Water can’t flow through the system properly when the heads of the sprinklers are clogged or dirty.

If this is the problem, you’ll usually see some sprinkler heads working and others that aren’t. You will need to clean and check the sprinkler heads for other problems in this case. There are a lot of steps involved in the right way to clean, so make sure to call a professional company to clean your sprinkler heads.

Water Line Obstruction

What happens underground is another common cause of low water pressure. If you have trees and big bushes in your yard or nearby, their roots can easily get into your water line. Roots can wrap around or even break through your water line over time, which can lower the pressure.

It is strongly suggested that you call a reliable service provider to help you find a solution to this problem.

Other Common Causes of Low Sprinkler Pressure

In addition to the main causes, there are a few other things that could be causing your sprinkler system to have low pressure:

• There are too many sprinkler heads in each zone, which makes the system work too hard.
• Pipes that are too small or old and cause friction loss.
• Municipal water supply pressure drops during times of high use.
• The zone valve isn’t working right or the timer settings are wrong.
• Water softeners or whole-home filters that slow down the flow.

How to Test for Low Water Pressure

Here are some quick tests you can do yourself to see if your system is having low pressure before you call a pro:
• Attach a pressure gauge to an outdoor spigot and check PSI (15–30 PSI for sprays, 30–50 PSI for rotors).
• Monitor your water meter for movement when no water is being used, which may signal a hidden leak.
• Perform a simple “bucket test” by timing how long it takes to fill a gallon container this reveals flow rate.
• Check sprinkler coverage and spacing against the manufacturer’s recommended ranges.

Fixes and Upgrades

Depending on the problem, solutions can be as simple as quick DIY fixes or as big as full system upgrades:
• Clean or replace clogged nozzles.
• Repair or patch small leaks.
• Reconfigure zones or split overloaded lines.
• Install a booster pump if city supply pressure is too low.
• Upgrade undersized piping in older systems.
• Switch to water-efficient rotary or low-flow nozzles.

For more complex issues, Andy’s Sprinkler, Drainage & Lighting can provide professional service to restore your system to peak efficiency.

Preventive Maintenance Tips

To keep water pressure consistent and avoid major repairs:
• Flush the system seasonally to clear debris.
• Clean filters and sprinkler heads regularly.
• Inspect valves and lines for early signs of wear.
• Winterize your system before freezing temperatures.
• Consider installing a smart controller to optimize watering schedules.

Choose Andy’s Sprinkler, Drainage, & Lighting Today!

If you’re dealing with any of the issues outlined above, then it’s time to pick up the phone and call Andy’s Sprinkler, Drainage, & Lighting, find out which location offers sprinkler repair near you. We offer top-notch sprinkler system services and we can ensure your yard is ready to look its best! Contact us today to schedule an appointment.