Checking sprinkler water pressure is quite simple. Attach a pressure gauge to an outside hose spigot to check source pressure. To check sprinkler head pressure, insert the end of a pitot tube into the stream of water coming from a nozzle.
How your sprinkler system runs is highly dependent upon water pressure. You want the source pressure and the pressure coming out of the heads to be within an ideal range for optimum efficiency.
Why is water pressure important?
Water pressure is critical because it impacts how your sprinklers run and their efficiency. If the pressure is too low or too high, you’ll see decreased efficiency and perhaps other problems in your lawn and system.
Problems caused by low water pressure
A sprinkler system—whether traditional or smart system—with low water pressure will show a significant drop in its efficiency because the heads won’t spray correctly.
- Sprinkler heads may not pop up and seat themselves when the system is running. Especially those furthest away from the water source.
- Spray heads or rotors may have uneven spray patterns and won’t spray as far as they should. This means the water will not reach the spray pattern of adjacent heads, and you’ll have dry, brown spots in your lawn.
The result, quite often, is donut-shaped zones of green grass around sprinkler heads surrounded by brown, dying grass.
Problems caused by high water pressure
Like low pressure, high water pressure causes problems, too, but they are different.
The first—and likely the most concerning—is the potential system damage high water pressure can cause.
Like putting too much air into a balloon, an irrigation system’s components can break or burst if the pressure gets too high. High pressure can break sprinkler heads, but the most common damage occurs where pipes are joined with PVC fittings.
The second problem is the loss of watering efficiency. This issue is more common than system damage but appears slightly different than when there is low pressure.
When the water pressure is too high in a sprinkler system, the water sprays from nozzles in a fine mist instead of larger droplets. The fine mist has a much greater chance of evaporating before it falls to the ground, making it so your grass doesn’t receive the moisture.
High water pressure in a system can also increase the flow rate, putting out much more water than the system is designed for. Even though the water potentially evaporates and doesn’t reach the lawn.
What is the ideal water pressure?
System water pressure varies based on location and other factors, but the ideal residential pressure for a sprinkler system is between 40 and 60 pounds per square inch (psi).
To run an Irrigreen smart sprinkler system, you need constant pressure between 40 and 80 psi.
How to measure water pressure at the source
Measuring the water pressure at the sprinkler system source is relatively straightforward. You’ll need a liquid-filled pressure gauge. They cost about $20 and are available at your favorite local hardware store, big box stores, and many online retailers.
- With the water off inside and outside the house (including all sinks, showers, washing machines, etc.), attach the pressure gauge to a water spigot outside your house.
- Open the spigot to turn on the water.
- Once the needle on the gauge stabilizes, read where it falls. This is the water pressure in psi.
How to measure water pressure at a sprinkler head
Good water pressure at the source doesn’t always guarantee you’ll see that same pressure at each sprinkler head. So if you’re seeing those donut-shaped rings around your heads or water is spraying in a fine mist, it’s wise to check the pressure at the heads.
To do this, you’ll also need a liquid-filled pressure gauge. However, as your nozzle doesn’t have threads to attach a gauge to like a spigot, you also need a little gadget known as a pitot tube.
A pitot tube is a small brass instrument that looks like the end of a water flosser. When the end of the tube is inserted into a stream of water, it measures the pressure. The pitot tube attaches directly to the pressure gauge or can be connected via a flex hose.
More often than not, you’ll need to purchase one online, or you may be able to find one at a local sprinkler supply store. These instruments are also called a headchecker gauge with pitot tube.
Using one is similar to measuring the water pressure at a source.
- Make sure all plumbing fixtures inside and outside the house (sinks, showers, hoses, etc.) are turned off.
- Turn on a single zone of your sprinkler system.
- Once a head pops up and starts spraying water, insert the open tip of the pitot tube into the nozzle directly in the stream of water.
- Once the needle on the gauge stabilizes, read where it falls. This is the water pressure in pounds per square inch (psi).
- Repeat as necessary with other heads.
