Educational tool · daily and two-hour comparisons

Will my well keep up?

Compare a documented usable water-supply rate with your chosen daily household allowance and Penn State’s conservative full-day-in-two-hours planning benchmark.

Developed with AI assistance; not reviewed by a licensed well or pump professional. Educational fixed arithmetic only. No individual professional or AI assessment occurs. Method and sources · Conditions of use

Your documented scenario

People in the householdEnter a whole number from 1 to 20.

Chosen daily allowance (US gal/person/day)Penn State gives 80–100 as planning context. Choose from actual records and documented fixtures where available.

Additional household demand (US gal/day)Enter a known zero or separately documented daily use not already included in the per-person allowance. Avoid double-counting.

Documented usable supply rate (US GPM)Use no more than both the sustainable well-test rate and installed transfer delivery under actual conditions. A tap bucket test, pump nameplate, guess, or all tested yield alone does not establish this input.

Available pumping hours per dayEnter 0–24 documented hours, or the exact word unknown. Do not assume 24 hours.

Documented supply during the two-hour comparisonContinuous requires evidence that the documented rate is available for the full two hours. If the daily schedule is known, it must include at least two available hours.

I confirm the household scope, allowance and additional demand; every numeric value and zero is documented, and unknown availability is marked unknown; the usable rate is supported by both sustained well evidence and installed delivery; the stated pumping availability is documented; and I have not counted gross borehole volume, pressure-tank volume, or other storage as supply.

Values stay in this browser calculation and are not sent to an AI provider or stored by this tool.

Your planning comparisons

Enter the documented values and confirm the conditions.

Method yield-1.0.0 · Sources checked September 8, 2026 Toronto.
Penn State Extension, “Using Low-Yielding Wells,” updated September 8, 2025: What Is Well Yield; Peak Demand; Storage Tank Capacity · Penn State Extension, “Water System Planning: Estimating Water Needs,” updated May 29, 2025: Estimating Home Water Use Needs and peak-demand planning

Method, terms, assumptions and sources

Sustainable well yield is the pumping rate that can be maintained without lowering water below the pump intake. Installed pump delivery is what the installed system can transfer under actual conditions. This worksheet’s usable rate cannot exceed either one. Wellbore storage is water standing in the well and may fall with seasonal water levels. Pressure-tank drawdown is the smaller usable volume delivered between pressure-switch limits, not the tank’s nameplate volume. Intermediate usable water is water available in a nonpressurized reservoir between its operating limits.

Daily demand is people × chosen allowance + additional demand. With known pumping hours, daily supply is usable rate × 60 × hours and daily balance is supply minus demand. Unknown hours produce an explicit unknown daily supply and balance.

Penn State recommends planning for the projected full-day water use during a two-hour peak period. This calculator compares the visitor’s chosen daily demand with documented supply during exactly 120 minutes. Continuous supply contributes usable rate × 120; “none” contributes zero; unknown remains unknown. The average comparison rate is demand divided by 120. Exact equality is shown as no reserve. This conservative benchmark is not a claim that the household actually uses water uniformly or consumes its full day’s volume in two hours.

Penn State’s low-yield article separately gives a 100-US-gallons-per-resident rule of thumb for a reservoir intended to hold a full day’s use. It is displayed as a separate reference, not substituted for the visitor’s daily estimate or used to select a tank.

Product bounds are 1–20 people, 1–250 US gal/person/day, 0–5,000 additional US gal/day, 0–100 US GPM, and 0–24 available pumping hours. These are worksheet limits, not engineering standards. Known zero is different from missing or unknown information.

Teaching example: four people × 100 US gal/person/day, no additional demand, a documented 1 US GPM usable rate, 16 available pumping hours, and continuous two-hour availability. Daily demand is 400 US gal; daily supply is 960 US gal; daily balance is +560 US gal. The two-hour supply is 120 US gal, leaving 280 US gal uncovered; the average two-hour comparison rate is 3.3333 US GPM. This example is not your property.

Primary sources: Penn State Extension, “Using Low-Yielding Wells” (updated September 8, 2025; What Is Well Yield, Peak Demand, Pressure Tank Storage, Intermediate Storage, Storage Tank Capacity, Well Pump Capacity, Borehole Storage) and Penn State Extension, “Water System Planning: Estimating Water Needs” (updated May 29, 2025; Estimating Home Water Use Needs and peak-demand planning). Sources checked September 8, 2026 Toronto; WDG method yield-1.0.0.