Well Pump Short-Cycling Calculator

Pressure tank failure, locked-rotor surge waste & pump lifespan risk.

A waterlogged pressure tank can cycle your submersible pump dozens of times per hour — each 2-second startup pulls up to 400% more amps than steady run.

Well System Profile

Listen at the pressure switch — count complete on/off cycles over 10 minutes.

Daily draw: 300 gal at 75 gal/person.

Dual Results Panel

1) Monthly electricity cash waste

Surge-only bill waste / month

Extra startup surges vs a healthy 2–5 cycles/hr tank.

Extra cycles / day
Locked-rotor amps
kWh wasted / day
Daily water draw

2) Pump failure risk meter

Expected pump life

Baseline: $2,500 submersible pump · 15 yr life with proper tank pre-charge.

Practical tips & common mistakes

Check tank pre-charge with water off

Measure bladder air pressure with pump power off and tank drained to system pressure — usually 2 psi below cut-in on the switch.

Replacing the pump first

A new pump on a waterlogged tank will short-cycle again in weeks. Tank or bladder replacement is often the real fix.

Count cycles scientifically

Listen for 10 minutes: cycles × 6 = rough hourly rate. Normal is 2–5/hr when no tap is open.

LRA vs running amps

This tool isolates startup surge waste — steady-state pumping cost is separate on your utility bill.

Note: Surge waste isolates locked-rotor startup energy (2 sec × 400% run amps) on cycles above a healthy 3.5/hr baseline — not steady-state pumping. Check pressure tank air pre-charge (typically 2 psi below cut-in). This is a diagnostic estimate, not a pump curve analysis.