Why Is My Irrigation System Losing Pressure?
UK Flow Centre problem guide
Find out whether the problem is supply, restriction, leak or demand
Pressure loss is not one fault. The point at which it happens — everywhere, one zone, or only at the far end — is the best starting point.
1. Read where the pressure is lost
- Every zone is weak: investigate the water source, pump duty, supply pressure, main filter and any restriction before looking at individual sprinklers.
- Only one zone is weak: look at that valve, its filter or regulator, zone pipework, a local leak, or too many outlets running together.
- The first heads work but the far end does not: pipe size, run length, elevation change or excessive flow demand are likely contributors.
- Pressure starts normally then drops: check a falling tank or borehole level, a blocked filter, pump control or a leak that becomes apparent under pressure.
2. Work through the system in order
Water source and pump
Confirm the pump or incoming supply can meet the required flow at the required working pressure. Maximum flow and maximum head figures do not describe the same operating point. A pump that is suitable for one sprinkler or outlet may not suit several operating together.
Filters, valves and controls
Inspect filters and strainers for restriction. Check that isolation valves are fully open and that control valves, pressure regulators and pump controls are set and operating as intended. A pressure regulator limits downstream pressure; it cannot correct an undersized pump, blocked filter or badly sized main.
Pipework and leakage
Pipe friction rises with flow and distance. Small pipe, long runs, unnecessary fittings and sudden reductions can consume useful pressure. Visible wet ground, a meter moving when no water should be used, or a pump cycling unexpectedly can point to a leak, but underground faults may need formal investigation.
3. What may help — after the cause is identified
- Blocked filtration: clean, repair or resize the filtration arrangement for the expected flow and water quality.
- Excessive zone demand: reduce the number of outlets operating together or redesign the zone.
- Pipework restriction: remove unsuitable bottlenecks and review the main size, run length and fittings.
- Leak or damaged valve: locate and repair the fault before changing the pump.
- Inadequate pump duty: select a pump from its curve against the actual installation duty.
Before you ask for help
Send the pump model, pipe sizes, lengths and elevation changes, number and type of outlets running, pressure readings if available, water source and a sketch of the system. This is enough to start separating a design issue from a fault.
Read the pump buying guide Shop pumps Shop filtration Shop irrigation pipe
Technical guidance from UK Flow Centre, operated by JK Irrigation Ltd.