Determine if your well can meet your household and irrigation needs using GPM pump test data.
Before building on rural land or buying a property with an existing well, understanding that well's actual yield is critical. A well yielding 1 GPM may struggle to supply a family of four year-round, while a 10 GPM well can support livestock, irrigation, and a full household with ease. Enter your pump test results below to see exactly what your well can deliver.
Well yield is measured in gallons per minute (GPM) and reflects the rate at which water flows into the well casing from the surrounding aquifer. A pump test — also called a well performance test — measures this by pumping water at a sustained rate for 1–4 hours and monitoring whether the water level in the well stabilizes. The sustainable yield is the rate at which the well can be pumped without drawing the water level down to the pump intake.
GPM ranges and their practical meaning for residential use:
Important: never run a residential well at 100% of tested capacity. Hydrogeologists recommend a maximum daily draw of 70% of capacity to allow aquifer recharge and maintain a buffer during drought conditions when aquifer levels drop. A well that tested at 5 GPM during a wet spring may yield considerably less in August of a drought year.
If your well yield falls short, solutions include: adding a storage pressure tank to buffer peak demand, installing a cistern (1,000–5,000 gallon) that fills slowly overnight, scheduling high-demand activities during off-peak hours, reducing irrigation through drip systems, or hydrofracturing (also called hydrofracking) the well to increase yield from existing fractures in the bedrock.
Most state health departments and mortgage lenders consider 5 GPM or more to be a good residential well. Some states set the minimum at 3 GPM. Anything over 10 GPM is excellent and supports irrigation and livestock in addition to household needs.
The USGS estimates average indoor residential water use at 80–100 gallons per person per day in the U.S. Conservative rural households may use 50–75 gallons per person per day through conscious water-saving practices (low-flow fixtures, efficient appliances, short showers).
A rough estimate for outdoor irrigation during the growing season is 1 inch of water per week per acre, which equals approximately 27,154 gallons per acre per week or about 3,879 gallons per acre per day. This varies widely by crop, soil type, climate, and evapotranspiration rate.
Absolutely. A professional pump test ($300–600) is one of the most important due diligence steps when buying rural property with a well. Ask for the original well driller's log (required in most states) and insist on a 4-hour sustained pump test at a rate that meets your expected demand. Test the water quality for bacteria, nitrates, and local contaminants of concern as well.
A well "running dry" typically means the pump is drawing water faster than the aquifer can recharge — the well isn't actually empty, it's depleted temporarily. Solutions include: reducing pumping rate, adding storage, deepening the well, hydrofracturing, or in extreme cases, drilling a new well into a deeper aquifer. Seasonal dry spells are common in shallow bedrock wells during late summer droughts.