How to Choose the Right Sprinkler for Your Water Supply

Choosing the right sprinkler starts with knowing what your water source can handle. Matching sprinkler requirements to your system’s pressure and flow (GPM) will help you get the best performance and avoid problems.

1. Know Your Water Pressure and Flow (GPM)

Sprinklers require a specific water flow (gallons per minute, or GPM) and pressure to work properly. To determine the largest sprinkler your pump or water source can support, you’ll need accurate information about both pressure and GPM.

Ways to Determine Your System Capacity

Using a pump curve: If you have an irrigation pump, check the pump curve. This chart shows how much pressure and flow the pump can deliver at different operating points and is the most reliable way to size your sprinkler.
For non-irrigation pumps: If the pump is not designed for irrigation, a good rule of thumb is to assume it can only deliver about 50% of its listed maximum specs. Pressure and flow are linked, so you cannot get the maximum rating for both at the same time.
Measuring directly: If you don’t have any data, you can:
- Use a pressure gauge to measure operating pressure.
- Perform a flow test (time how long it takes to fill a known volume) to calculate GPM.

2. Match Sprinkler Requirements to Your System

Every sprinkler has a range of operating conditions. Product charts usually list:

Minimum and maximum operating pressure.
Required GPM at different pressures for each nozzle size.

Larger nozzle sizes always require more GPM. To choose the right sprinkler or nozzle:

Compare your pump’s pressure and GPM to the sprinkler performance table.
Select a sprinkler and nozzle size that your system can supply comfortably, not at the very edge of its capacity.

3. Account for Pressure Loss in the Supply Line

Water loses pressure as it moves through pipes due to friction. If you don’t account for this, the sprinkler may receive less pressure than expected and underperform.

Pipe Size and Flow Rate

Use an irrigation pressure loss calculator whenever possible to choose the correct pipe size for your flow rate and distance. If you do not have a calculator, you can use these general guidelines:

For flows over 10 GPM, use at least 1-inch pipe.
For flows over 50 GPM, use at least 2-inch pipe.
For flows over 100 GPM, use at least 3-inch pipe.

Long Pipeline Runs

For pipe runs longer than 100 feet, always use a pressure loss calculator.
Check that, after friction losses, there is still enough pressure at the sprinkler to meet its minimum operating requirement.

Putting It All Together

By:

Knowing your water supply’s pressure and GPM,
Matching those numbers to the sprinkler’s performance charts, and
Allowing for pressure loss in the piping,

you can select a sprinkler that operates efficiently and provides even, reliable coverage for your irrigation system.