Yield is the rate at which a well can sustainably produce water, measured in gallons per minute (GPM). It's the second most important spec for a domestic well after depth — and unlike depth, it directly affects whether your house will run out of water during a long shower.
The benchmarks
- 5 GPM sustained — Utah's accepted minimum for a new domestic well. Matches the FHA mortgage standard and the National Water Well Board recommendation. Below this, a cistern is recommended.
- 10–20 GPM — Comfortable for a single-family home with light landscape irrigation
- 20+ GPM — Plenty for heavy irrigation, livestock, or larger property use
How yield is tested
Drillers run a pump test on completion — typically 4 hours at a target pumping rate, watching how the static water level draws down and how quickly it recovers. The result is reported on the well log as the sustained yield.
What affects yield
- Aquifer transmissivity — how easily water moves through the formation
- Production zone thickness — a 50-foot productive layer pumps more than a 10-foot one
- Casing/screen design — wire-wrap screens give 3–10x more inflow than perforations
- Depth below static water level — more drawdown available = more yield
- Seasonal water table — yields can drop in late summer or drought years
What if yield is low?
For a Utah domestic well, anything under 5 GPM means you'll want a buffering setup:
- 1,000–2,500 gallon cistern — fills slowly from the well at 1–4 GPM, then a separate pressure pump pulls from the cistern at full pressure for the house. Total cost: $3,000–$8,000.
- Larger pressure tank — 200–500 gallons of pre-pressurized storage instead of the typical 40–80 gallons. Cheaper than a cistern, less storage.
- Variable-frequency-drive constant-pressure pump — can maximize the steady-state yield from a marginal well.
What our calculator estimates
The Utah Water Well Cost Calculator reports the expected yield in GPM based on nearby driller logs. When measured GPM data isn't in the logs, the calculator infers yield from water-bearing zone thickness in the lithology (a rough but useful proxy). The result is graded A through F based on the benchmarks above, with a treatment note (e.g. "cistern recommended" for low-yield areas).