How Many Sprinkler Heads Per Zone? (Find Out Now!)
A sprinkler system can bring up the value of your home, but more importantly, a sprinkler system makes your life easier! Since professionally installed sprinkler systems can get costly, many have turned to DIY installation kits. But before you start digging, first find out how many sprinkler heads you can use per zone. And it doesn’t hurt to understand precisely how a sprinkler system works.
A sprinkler system is made up of the control box, the valves that control the water supply to the sprinklers, the network of underground pipes, and the sprinkler heads that irrigate the yard. The control box, sometimes called a controller timer or irrigation controller, sends electrical signals to the appropriate electric valve, opens it, and sends a surge of water to the desired zone.
To find out how many sprinkler heads you will need for each zone, you’ll first need to calculate your home’s water pressure and water flow rate. You’ll need a water pressure gauge to determine the pressure. Calculate the necessary flow rate of all your sprinkler heads in gallons per minute. Divide by the GPM used by your recommended sprinkler for how many sprinkler heads can be used per zone.
Getting the Right Measurements
- Container with known capacity, such as a 5-gallon bucket
- Water pressure gauge
Measuring Flow Rate in GPM
You can measure the flow rate of your home’s water in gallons per minute or GPM. To find the flow rate, use a container with a known capacity, such as a 5-gallon bucket. Turn off all appliances in the house that use water, like your dishwasher or ice-maker. Then, fill your container with water using your outside water source. Make a note of how long the container takes to fill.
Find the flow rate by multiplying the container’s size by 60, then dividing it by the number of seconds it took to fill the container. For example, multiply your 5-gallon bucket by 60 to get 300. If the bucket took 33 seconds to fill, divide 300 by 33. The result is 9.09 GPM or 9 gallons per minute.
Determining Water Pressure (PSI)
Measure your home’s water pressure in PSI or pounds per square inch. Typically, a home’s water pressure should be between 40-55 PSI. It requires less math, but you will need a pressure gauge.
To determine your home’s water pressure, locate the outside spigot closest to your water meter. Ensure that all the water inside your home is off and that any water-using appliances such as dishwashers and ice-makers are off. Attach your pressure gauge to the outside spigot and turn the faucet on full blast. The pressure gauge will tell you your water pressure in PSI.
Calculating How Many Sprinkler Heads Per Zone
Once you know your home’s water flow rate and water pressure, you can calculate how many sprinkler heads you will need per zone.
Step One: Determine the Total Number of Sprinkler Heads You Will Need
Map out your landscaping, keeping in mind that plants in the same zone need to have similar watering requirements. Considering each sprinkler’s reach, determine how many sprinkler heads you will need in total.
Step Two: Choose Which Sprinkler Heads to Use
It’s a good idea to stay with the same brand and type of sprinkler head. Since the water pressure can vary depending on the nozzle head, keeping your sprinklers uniform ensures that your sprinkler system runs optimally.
Check manufacturer’s notes for water flow for different water pressures. Using your measurements from the pressure gauge, find a sprinkler head that will work with your home’s water pressure. Make a note of the sprinkler head’s water flow in gallons per minute.
Strep Three: Divdie Your Home’s Flow Rate by the GPM of the Desired Sprinkler Heads
Refer to the sprinkler heads that are available to you according to your home’s water pressure. Divide your home’s water flow rate in GPM by the GPM listed for the sprinkler heads recommended for you on the manufacturer’s chart. Round down for the number of sprinkler heads you can use for a zone.
For example, if my home’s water flow is 9.09 gallons per minute or 9 GPM, and the sprinkler heads I want work with my home’s water pressure of 50 PSI to use 5.1 gallons of water each minute, I get 1.8.
Step Four: Round Down
Round your answer down to get the number of sprinkler heads you can use per zone.
Because I got 1.8, I can only use one sprinkler head per zone.
How Sprinkler Heads and Zones Work
A sprinkler system is divided into zones. Each zone feeds water to sprinkler heads in different areas of your lawn, and a valve supplies each zone. The controller, or control box, sends a signal to the valve to open. Essentially, one valve is equal to one zone.
One zone can supply just one sprinkler head, or it could supply many. How many sprinkler heads per zone will largely depend on your home’s water pressure and water flow. The water pressure is measured in pounds per square inch or PSI. The water flow is measured in gallons per minute or GPM.
Related Guide: Sprinkler Heads Not Popping Up?
Types of Sprinkler Heads
Spray heads emit a steady spray of water over an area, like a fountain. If your water pressure is less than 40 PSI, consider using a spray head. Spray heads often have interchangeable nozzles, so you can switch between circle or half-circle or adjust them to your landscaping.
Rotor heads emit a rotating stream of water over an area. These sprinkler heads are popular with commercial landscaping and work best with high water pressure. Although we once knew them for their iconic sound, impact rotor sprinklers have evolved to a quiet and low-maintenance machine. Multi-stream rotors are especially beautiful to watch in action.
Rotary nozzles emit multiple streams of water that rotate around the nozzle. These sprinkler heads are an excellent alternative to spray heads, which produce a mist, some of which never even reaches the lawn. Rotary nozzles are a cheap and efficient way to keep your lawn green while conserving water.
Common Issues with Zoning Sprinkler Heads
Multiple Zones Running
Some sprinkler valves require a minimum amount of water to keep them open. If not enough water is moving to keep the valve open, the zone may stop working or even begin to leak.
Frozen Pipes in Winter
Some people worry about their sprinkler systems freezing during the colder months, but that’s only for sudden cold snaps. To prepare for winter, drain your sprinkler system and set the timer off. If temperatures dip below zero, you may need to blow out your pipes with an air compressor.
Low Water Pressure
If your sprinkler system doesn’t have any water pressure, you could have too many sprinkler heads in a zone. Since a single valve controls all the sprinkler heads in a single zone, too many heads in a zone will weaken water pressure.
Make sure that no water is being used inside the house as you measure the water pressure outside. Turn off all appliances like ice makers, washers, dishwashers, and showers. Using any water during this time will affect the pressure gauge, causing your calculations to be incorrect.
Warning! If your water pressure is ever above 80 PSI, you will need to install a water pressure regulator.
Can I add another sprinkler head to an existing zone?
Expanding your existing sprinkler system is a simple process, but it will require additional trenching. Once you have dug the new trenches, you will need to cut and glue your PVC pipes to fit your new system. Keep in mind that each zone supplies all its sprinkler heads simultaneously, so installing too many sprinkler heads in one zone will lower the water pressure. If your sprinkler system’s water pressure is too weak in one zone, try removing one sprinkler head.
How do I calculate the sprinkler area?
To calculate the reach of your sprinkler system, you may need to take measurements of the affected area first. Remember when laying out your sprinklers that overlap is good. If using a rotary sprinkler, make sure that the distance between your sprinklers is not more than the water pressure PSI. For example, if my water pressure is 45 PSI, my sprinkler heads should not be more than 45 feet apart, or I may end up with some dry patches.
Why are some sprinkler zones not working?
Make sure the main valve is open. An electrical problem could be causing the zone to malfunction. The timer or sensor could have worn out. Or, a bad connection or controller could be the culprit.
When it comes to how many sprinkler heads you can use per zone, it’s a matter of how much water you can run out of a single valve at one time. Once you know your home’s water flow rate in GPM and the water pressure (PSI), you will be able to calculate how many sprinkler heads you can use per zone.
HK Sloan is a freelance writer currently covering DIY Home Improvement, Health, and Lifestyle. Sloan is passionate about improving situations for less, whether it be working on mind, body, or home.
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