Drip Irrigation Index
All irrigation guides

Troubleshoot low or uneven drip irrigation flow

First find the pattern. A whole weak zone, one dry row and a few dry emitters point to different parts of the system.

Find the first check for your symptom

Every row is weak
Check the supply and valves, then compare pressure on both sides of the filter.
One row or its far end is dry
Inspect the row start for restrictions and check pressure at its inlet.
Only a few emitters are weak
Check the filter and flush the line before inspecting individual outlets.

Every row is weak

Check the supply, any partially closed valves and the filter. Compare pressure before and after the filter with the same zone running. If the entire zone improves when fewer rows are open, calculate zone demand and check the supply and regulator’s rated conditions.

Check the actual tape code and pressure. A replacement tape can draw more water even when it has the same outside appearance and emitter spacing.

One row or the far end is dry

Inspect the row start, tape for kinks, and the end closure. Measure pressure at the inlet to the weak row. An uphill or very long row can have weak delivery at its end even when the inlet looks normal. Check the manufacturer’s chart for that model and slope.

To see where output drops, collect water from a few representative outlets near the beginning, middle and end for the same amount of time. Compare the volumes before and after cleaning or flushing. One outlet can be atypical, so sample more than one at each position.

Only scattered outlets are weak

Check the filter condition and flush the laterals as the manufacturer directs. If the same outlets remain weak, inspect for damage or plugging. Collect a water sample when symptoms return across multiple rows or you find deposits.

Keep a short record of which zones are affected, pressure under flow and the changes you made. Compare the same zone under the same conditions after each fix.

Look up the specifications for your drip tape or calculate flow for your rows.

Sources