Well Water Yield Calculator

Daily Yield is calculated entirely from Recovery Rate (gallons per minute) times 60 times 24 — the rate at which the aquifer refills the casing after being drawn down. Well Depth and Static Water Level are only used to compute the Water Column figure, which describes how much standing water is available to the pump, not how fast the aquifer replenishes it. A deep well can still have a poor daily yield if its recovery rate is slow.

Sustainable Rate is simply your Recovery Rate expressed in GPM — the continuous flow the well can support without depleting. Daily Yield is that same rate scaled up to a 24-hour total in gallons. They describe the same underlying capacity at two different time scales, one instantaneous and one daily.

The calculator assumes a typical household concentrates its water draw into roughly 8 hours a day — mornings and evenings — rather than spreading it evenly across 24 hours. It compares twice your peak hourly demand against twice what the recovery rate could replace in that same window, floored at zero, so a well that easily keeps pace during that window shows no buffer requirement at all.

Yes. Pump Run Time only reflects how long the pump must run at its rated flow to deliver your entered daily usage — it isn't checked against the well's recovery rate. If your pump is rated well above what the aquifer can replenish, the calculator can report a run time that would draw the well down faster than it recovers, which is exactly what Surplus/Deficit is meant to catch separately.

Every other output — Sustainable Rate, Daily Yield, Surplus/Deficit, and Storage Buffer Needed — is derived directly from that one number. A guessed or outdated recovery rate propagates its error into every result, while a professionally measured drawdown/recovery test gives you a defensible figure the rest of the calculation can actually be trusted to build on.