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Pump GPM Test

Check how many gallons per minute a lift station pump is really moving

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SAFETY

Take every measurement from the top, with a tape or weighted line lowered through the hatch. Do not enter the wet well. Use this only if you are trained, qualified, and authorized to work at lift stations, and follow your own safety procedures. This tool is for general information only. Chambers Services, LLC, does not supervise or take responsibility for any test done with it.

How the test works

  1. Pump the wet well down so the level sits about 18 inches below the inlet pipes.
  2. Step 2: With the pump off, time how long the level takes to rise 12 inches. That gives the water coming in.
  3. Step 3: Turn the pump on and time how long it takes to pull the level down 12 inches.
  4. The pump is moving the water it removes plus the water that kept flowing in. The tool adds those together.
1

Wet well size

Use the inside diameter of the wet well. Keep the same distance for both timed steps. The test assumes a straight-sided round well.

2

Pump off: time the level rising

Level starts about 18 inches below the inlet pipes. Start the watch when the level is at your starting mark, and stop it when it has risen the full distance above.

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3

Pump on: time the level dropping

Start the pump and the watch together. Stop the watch when the level has dropped the same distance.

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Result

Enter the wet well size and both times to see the pump GPM.
Optional: pump efficiency

Uses the GPM from above. Add the pump head and the motor readings to see how much of the electric power ends up moving water. Skip this if you only need the GPM.

Power factor is on the motor nameplate. If you do not know it, 0.85 is a common estimate, which makes the result approximate. Read the amps while the pump is running during Step 3.

Results are an estimate. Level readings, pipe volume, and changing inflow can move the number.