When sprinkler flow drops during peak demand, start by checking the available supply pressure and flow before assuming the pump has failed.
It was fine at the house. The pressure dropped to 18 PSI at the last head. That is not enough.
What type of pump do you need for your irrigation system?
You need either a centrifugal pump or a submersible pump. Centrifugal pumps sit above ground and pull water from a source. Submersible pumps sit in the water and push it up.
Centrifugal pumps cost $150 to $400. Submersible pumps cost $300 to $800.
It handles 30 GPM at 50 PSI. Submersible pumps work better for deep wells over 25 feet. Both types need priming before they work.
A jet pump is another option for shallow wells under 25 feet. Jet pumps cost $200 to $500. They work by creating suction.
They are less efficient than centrifugal pumps. The efficiency loss adds up over a full season.
A 1 HP centrifugal pump delivers about 20 GPM at 40 PSI. A 1 HP jet pump delivers 10 GPM at the same pressure. The difference is significant.
Choose your pump type based on your water source depth. Surface water needs a centrifugal pump. Deep wells need a submersible. support/irrigation-system-design-guide/) before buying a pump. The pump must match your zone flow and pressure needs.
How do you calculate the right pump size and horsepower?
Calculate total flow first. Add the GPM of every sprinkler head on your largest zone. Then add pressure requirements.
Include elevation gain, pipe friction loss, and head operating pressure. Use this formula: Total Head = Elevation Head + Friction Loss + Operating Pressure. 433 PSI per foot of rise.
66 PSI. Friction loss for a typical zone is 5 to 10 PSI. Operating pressure is 40 PSI for rotors. Total needed is 54 to 59 PSI.
Convert that to horsepower. A 1 HP pump at 40 PSI delivers about 20 GPM. 5 HP pump delivers 30 GPM at 50 PSI.
A 2 HP pump delivers 40 GPM at 55 PSI. 5 HP to $600 for 2 HP.
The pump runs at 80% capacity instead of 100%. This extends pump life by years. 5 HP pump cost $350.
Each zone runs at 12 GPM and 50 PSI. The pump cycles on and off with a pressure switch.
It only runs when a zone is active. This saves electricity and wear.
How do you install a lawn irrigation pump?
Install the pump as close to the water source as possible. Every foot of suction pipe reduces efficiency. Keep suction lift under 15 feet for centrifugal pumps.
Use a foot valve with a strainer at the water source. This keeps the pump primed and stops debris. 5-inch schedule 40 PVC.
25-inch PVC to the main line. The pump sits on a concrete pad. It costs $50 for the pad materials.
Wire the pump to a dedicated 240-volt circuit. Most pumps over 1 HP need 240 volts. 5 HP pump draws about 10 amps at 240 volts.
Use 12-gauge wire for a 20-amp circuit. Install a disconnect switch within sight of the pump. This is required by code.
It cost $200 for the circuit and disconnect. The pump cost $350.
The fittings and pipe cost $80. Total installation was $630. Follow the pump manual for priming instructions.
Fill the pump housing with water before starting. Running it dry destroys the impeller in seconds. A dry-run pump costs $150 to replace the seal.
Why is your irrigation pump losing pressure and how to fix it?
Three things cause pressure loss. A clogged intake strainer, a leaking suction line, or a worn impeller. Check the intake strainer first.
Debris blocks the water flow. A clean strainer fixes 60% of pressure problems. Clean mine every two weeks during peak season.
It takes five minutes. Unscrew the strainer housing. Rinse the mesh with a hose.
Reinstall and test. If pressure returns, you found the problem.
Suction line leaks are harder to find. Air gets pulled into the pump through a tiny crack. The pump loses prime and pressure drops.
Test for suction leaks by pouring water over suspect joints. Replace the damaged section of pipe.
5-inch PVC costs $2. A coupling costs $1. The fix takes 30 minutes.
Worn impellers happen after years of use. The impeller blades erode from sand and grit. A new impeller costs $30 to $80.
Replacing a worn impeller can restore lost pressure when inspection confirms erosion or damage. Record pressure before and after the repair, then keep up with filtration and routine maintenance to extend pump life.
Change the oil annually on pumps with oil reservoirs. A well-maintained pump lasts 10 to 15 years. A neglected pump fails in 3 to 5 years.
Check your pressure switch settings too. The switch turns the pump on at a low pressure and off at high pressure. Typical settings are 30 PSI on and 50 PSI off.
If the switch is set wrong, the pump cycles too often. That wears out the motor and contacts. A new pressure switch costs $15.
The adjustment takes 2 minutes. support/irrigation-controllers-complete-guide/) for maximum efficiency. The pump and controller work together to save water.
