The short answer. Yield is how fast the rock refills the well. Storage is the water already standing in the casing above the pump — roughly 1.5 gallons for every foot in a 6-inch casing. A household draws on storage during a peak and the yield refills it afterwards. A modest yield with a tall water column often serves a family better than a bigger yield with a short one.
Two Numbers, Not One
A bedrock well is a hole through granite lined with steel casing at the top. Water seeps in from the fractures the hole crosses and rises to a resting height — the static water level. Everything between that level and the pump intake is water you can use without the rock doing anything at all.
When a tap opens, the pump draws from that column. If the house uses water faster than the fractures deliver it, the level drops. When the house goes quiet, the fractures refill it. Yield sets the refill speed; the column sets how long you can outrun it.
Which is why the yield figure on an inspection report, read alone, tells you less than it seems. The median NH bedrock well yields about 15 gpm, and there is no state minimum — a well simply has to meet the household’s daily demand. Both figures are on our data page with the NHDES source.
Working Out What Your Well Holds
Three numbers do it: the depth the pump is set at, the depth to the static water level, and the casing diameter. The drilling record gives the first and often the second, if one exists; otherwise they can be measured during an inspection.
Find the column
Pump depth minus static water level. NHDES design guidance has the pump sitting 20–50 feet off the bottom to keep it clear of sediment, so on a 400-foot well the pump is commonly somewhere around 350–380 feet.
Multiply by 1.5
About 1.5 gallons per foot in a 6-inch casing. A different diameter changes that figure, so check before relying on it.
Compare it with your peak
Not your daily total — your busiest hour. That is where storage either covers the gap or does not.
| Well A | Well B | |
|---|---|---|
| Depth / pump setting | 400 ft / 370 ft | 400 ft / 370 ft |
| Static water level | 40 ft down | 300 ft down |
| Column above the pump | 330 ft | 70 ft |
| Stored water (× 1.5) | ~495 gallons | ~105 gallons |
| Yield | 3 gpm | 3 gpm |
| Two showers at once (5 gpm) | Falls 2 gpm behind — about 4 hours before the column is gone | Falls 2 gpm behind — about 50 minutes |
Same depth, same yield, very different houses to live in. Well A will never be noticed. Well B will sputter on the third shower of a full weekend, and the owner will be told the well is “weak” — when what it actually has is a short column. The static levels here are illustrative; yours is the number that matters.
Figures: 1.5 gal/ft storage, 20–50 ft pump clearance, 15 gpm median yield — NHDES DWGB-1-2; 2.5 gpm conventional showerhead — EPA WaterSense. All on our data page.
Why 3 GPM Is More Than It Sounds
A steady 3 gpm is 4,320 gallons over 24 hours — minutes in a day times the yield. EPA WaterSense puts the average American family at a little over 300 gallons a day at home. A 3 gpm well makes more than ten times that.
Households do not use water evenly, of course. The morning rush and the evening dishes and laundry carry most of the day’s demand into a few hours, and a conventional showerhead alone runs at 2.5 gpm. So the honest framing is not “is 3 gpm enough?” but “does the column cover the busiest hour, and does the yield refill it before the next one?” For most Lakes Region households on a 3 gpm well, the answer to both is yes.
If your well keeps up over a day and only runs short at peaks, there may be nothing wrong with it at all. Spreading the laundry out is a genuine answer, and costs nothing.
When a Low Yield Genuinely Is a Problem
Probably fine
- Runs short only when several things run at once
- Recovers within an hour or two of the house going quiet
- A tall column — water standing well above the pump
- The same pattern year after year, not getting worse
Worth a proper look
- The daily total does not cover demand. A quarter of a gallon a minute is about 360 gallons a day — barely over typical family use, with no margin
- A short column. Under about 100 gallons stored leaves little room for any peak
- Outdoor use on top. EPA puts roughly 30% of household use outdoors; a garden on a marginal well is where it tips
- Yield falling year on year, or the shortage arriving earlier each summer
Seasonal occupancy sharpens all of this. A camp that sits empty most of the year and then holds a dozen people in August is asking a modest well for its whole annual peak at once — which is the pattern our August guide covers.
What Actually Helps
| Cost | What it changes | |
|---|---|---|
| Managing peaks | Nothing | Spreads demand so the column is never asked for too much at once |
| Storage tank | $1,500–$4,000 | Adds storage above ground; fills at the well’s rate, delivers at the house’s. Does not depend on the rock |
| Hydrofracking | $2,000–$4,500 | Can raise the yield itself, if the rock is fractured. No guarantee |
| Bigger pump | — | Empties the column faster. Makes this exact problem worse |
The rule of thumb: if the well keeps up over a day, the problem is storage, not yield — and storage is the one fix whose result does not depend on what the granite decides. If it genuinely does not keep up over a day, hydrofracking is worth assessing first. A pressure tank, incidentally, is not storage: it is a cushion that keeps the pump from starting every time a tap opens, and a bigger one will not carry a peak.
Costs are our 2026 Lakes Region ranges; EPA indoor/outdoor split from WaterSense. See the data page.
Questions
Is a 3 gallon per minute well enough for a family?
Usually, yes. A steady 3 gpm is 4,320 gallons over a day against a typical family’s 300-odd. What it cannot do alone is run two showers at once — the water standing in the casing covers that, at about 1.5 gallons a foot.
How do I find my static water level?
The drilling record often lists it, if you have one. Otherwise it is measured during an inspection with the system at rest. Seasons move it, so a level taken in April and one taken in late August can differ.
Could the pump simply be set deeper for more storage?
Sometimes, by a little — every foot lower is another 1.5 gallons or so. But the 20–50 foot clearance off the bottom exists to keep the pump out of sediment, and setting it below that trades a storage gain for a shorter pump life.
Should I trust the yield figure on my inspection report?
Read it alongside how the test was run. A short test on a well with a tall column mostly measures the column, and can flatter the yield; a longer sustained test tells you more. Ask how long it ran and what the level did.