How to Adjust the Water Pressure and Flow Rate in Sprinklers

gloved hand reaching for sprinkler

Frustration abounds when your lawn, flowers, or garden spaces aren't getting the right sprinkler services. One of the most common issues with in-ground automated sprinklers is the incorrect pressure or flow. So, how do you adjust sprinkler system water pressure? The best way to address sprinkler flow control is to check the system piece by piece until you find the problem.

Common Causes of Low Sprinkler Pressure

sprinkler flowing into garden

Clogged or Buried Sprinkler Heads

No matter the type of sprinkler head you have, it can get clogged in the openings and cause some sprinklers to have low pressure or trickling flow. Others show heavy pressure and damage the plants.

Ensure the head isn't stuck in the grass and mud to fix this. If they are, take a moment to clear out the debris and dig around the sprinkler carefully with a hand trowel to remove grass or rocks that have grown over or washed into the sprinkler space.

Damaged Valves

Some valves control the water going to the sprinkler heads and also that direct water from the source down the pipes. Checking that all of these are in working order can help you identify the start of your low pressure.

Backflow prevention valves may also cause issues if it's not fully open. The valve in your backflow prevention system is manually operated, and having the handle set incorrectly can constrict the flow.

Damaged Underground Pipes

If you or the local utility companies have been doing any work in your yard that required digging, you may have damaged your pipes laid underground to transport water to the sprinkler heads. You'll often experience an exceptionally wet area in the yard where the crack, leak, or bend has occurred.

City Water Supply Disruptions

Sometimes, your low pressure isn't an issue with your system. But instead, it is an issue with the city water supply or a utility disruption. It isn't uncommon for a municipality to temporarily shut off water for a neighborhood to flush out the storm drains, repair a fire hydrant, or do other similar tasks.

Common Causes of High Pressure

Overly high water pressure in your sprinklers can damage the sprinkler heads, kill or damage your plants, or cause injury or discomfort to those who walk through the spray.

Alternatively, if the pressure is too high in some systems, it creates a mist or a fog instead of a steady rain-like sprinkling.

Municipal Water Pressure is Too High

Most sprinkler systems work best at a maximum water pressure of 40psi. If your city water is being pumped into your sprinkler system at a higher pressure, this could be the cause of the issue. In this case, you should invest in a pressure regulator valve rated to the current PSI.

This will reduce the water wasted, the damage to your landscaping, and the faster-than-normal wear and tear on your sprinkler system.

Sprinkler Head is Not Adjusted Correctly

Sprinkler heads typically come with an adjustment feature, allowing you to open or close the head valve to affect the flow rate and the pressure and adjust the coverage of your sprinkler zones.

Higher pressure means less water over a broader range; lower pressure means more water over a shorter range. You can carefully turn the sprinkler head adjustment screw to adjust the pressure and flow to adapt to your specific irrigation needs.

Clogs, Cracks, Leaks, and Other Damage

While these issues typically cause low pressure, a crack in the pipe can clog with clay and debris, causing the stress to build up in the pipes farther up the irrigation line.

These problems cause higher pressure in the sprinkler heads above the damage and lower pressure below the crack. You'll likely need to repair or replace this pipe to regain your flow and pressure control.

Common Problems with Sprinkler Systems

sprinkler valves

A few issues come up with all sprinkler systems through ordinary use. Annual maintenance prevents most of these occurrences, but you should still be aware of them:

Damaged pipes lead to flooding and lowered pressure.

Clogged sprinkler heads create uneven tension and distribute the water where it isn't needed.

Incorrect water pressure can cause floods or cracked heads, as well as damage to your landscaping.

Flow rate can contribute to water pressure issues and inadequate watering for your plants.

The critical thing to remember with sprinkler systems is that the problem can be a combination of multiple issues that cause the primary concern. You need to work from one end to the other to keep the system functioning in top order.

Troubleshooting Your Sprinkler System

You can figure out most sprinkler problems from the basic information about the sprinkler type. The most noticeable issue you'll uncover relates to the water pressure in one or more sprinkler zones. Alternatively, the pressure is too high and causes damage to your landscape.

Other issues causing high or low pressure may have nothing to do with your sprinkler system and everything to do with how you've got your zones set up or the municipal water supply struggles.

Further, changes in elevation from the origin point of your sprinkler system to the output heads can cause pressure changes that can affect the efficiency of your irrigation design.

Control Valve Issues

If the malfunctions in your sprinkler system aren't from physical damage, you may need to adjust your sprinkler flow control valves throughout the system. There are valves at the start point, where the water flows in from the primary system, at each sprinkler head, and at each split point between sprinkler zones.

Some control valves are digital and are adjustable at a central control panel. Still, others are manual and will require careful attention and adjustment to each junction one at a time. Consider how a control valve works: when the system is cranked open, the water flows freely at whatever pressure the water system runs for your home. It only lets in a portion of that flow when the valve is closed.

Think of a hose valve on the side of your house, you rotate it one way to open it and the other to close it. If you open it all the way, water gushes out of your hose. If you close it most of the way but not entirely, it will trickle from your hose.

When you put a watering nozzle on the end of the hose and then turn the faucet valve, the water flows until it reaches the nozzle. Then when you squeeze the trigger on the nozzle, the water is released through the pre-set holes in the sprayer. The size and shape of these holes dictate the formation and spread of the water flow. A sprinkler works much the same way.

With your sprinklers, you'll want to set up a control valve or regulator system that can adjust your sprinkler zone's pressure, shape, and direction to water your landscape efficiently.

Suppose the control valve and regulator aren't doing enough to effectively control the watering patterns in your sprinkler system. In that case, it may be time to upgrade or switch to a different type of sprinkler.

Sprinkler Technology

sprinkler controls

With an upgrade or switch to a new style, there is an opportunity to outfit your system with higher efficiency technology to help you make the most of your sprinkler system. The whole idea of the modern sprinkler is to make your life easier and grow beautiful lawns and gardens without the hassle of scheduling waterings and keeping track of the time your sprinklers are on.

Pressure Regulator

You can purchase an additional tool to add to your irrigation checklist to help with pressure issues in your sprinkler system. A pressure regulator valve acts as a monitor for your home and garden water system. In most cases, you can install it on your own and set it to a specific pressure. It's designed to make adjustments to maintain that pressure throughout the operation.

Irrigation Timers

Your system may already have an irrigation timer that isn't working correctly. Before you spring for a whole new system, try troubleshooting the design you have in place. The most common issue with sprinkler timers is that if they're disconnected from the power grid, such as during a power outage, the timers all reset and need to be reprogramed.

The ideal timing for your sprinkler to run will depend on the type of landscaping you're irrigating, the climate of your region, and any special weather events that have recently passed or are in the near future.

You can program your sprinklers to run on set times and days, but there is no sense in running your system in the day's heat where the water will scorch your plants or in a torrential downpour. Make sure that your system has a manual override for specific circumstances to save money and your plants.

How Long Should I Run My Sprinklers?

You can estimate how long to run your sprinkler system by calculating how much your system produces and considering the water needs of your plants.

It's usually best to run sprinklers in the early morning, after the sun has risen but before the heat of the day peaks.

In some cases, you might consider a soaker hose to keep specific beds moist, especially in higher temperatures.

When to Call in a Professional

If you've troubleshot the system and still have issues, it may be time to bring in a plumber or irrigation specialist. Many permaculture specialists can help you figure out the best options for your specific piece of land that needs to be watered.

An irrigation specialist can look at all aspects of your system. They can then recommend the best alternatives for the current sprinkler system or catch a missed flaw or break and quickly fix it.

Water Pressure and Flow Rate in Sprinklers FAQ

What is the recommended water pressure for a sprinkler system?

Water pressure in a sprinkler system is both a matter of choice and a matter of what the system is designed to handle. Most sprinkler systems will have between 30 and 60 psi, though around 40 seems to be the most common number cited among sprinkler system experts.

Measure water pressure using a water gauge or a flow meter.

Why is my sprinkler system not getting enough pressure?

If you find that your sprinkler system's pressure is too low, it could be caused by a number of different issues. It is possible that your backflow preventer valve is not fully opening, which results in low pressure.

You may also have a leak in one of the sprinkler nozzles, which will affect pressure. Sprinkler heads may also be clogged, which will impede water flow.

Keep grass around sprinklers trimmed to prevent blockage and clean sprinkler heads regularly to prevent clogs.

How do I increase the water pressure in my hose sprinkler?

If your sprinkle water pressure is too low, check your backflow valves and make sure they are fully open. Clean off the sprinkler heads and remove any grass or debris around them.

If you do these things and the pressure is still low, you can turn the pressure manually. Find the adjuster near the water meter.

Be warned, however, that this will increase water pressure for every fixture and faucet in your home.

How do I adjust the pressure on my sprinkler head?

Rotate the sprinkler head to change the arc of the spray and adjust the flow of the water.

What is too much pressure in sprinklers?

Most sprinkler systems are designed to comfortably run at around 40 psi, though some systems may have as much as 80 psi. There is really no such thing as too much pressure as far as your lawn goes because the lawn can withstand even very hard rains.

However, there is such a thing as too much pressure for your sprinkler system. Consult your owner's manual, or look it up online, to make sure you keep your water pressure within the range of manufacturer-suggested settings.