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Well inspection and flow test in Butte County

The listing says the property has a well. That sentence contains no information. A well can make 40 gallons a minute all summer or two gallons a minute and quit by August, and both are described exactly the same way in the ad and in the disclosure. A flow test is how you find out which one you are buying. It runs $200 to $400. Call to get connected with a licensed local pump contractor.

What gallons per minute actually means

Yield is measured in gallons per minute, and the number is easy to misread.

Start with what a house needs. A shower is a couple of gallons a minute. A washing machine is a few. A hose bib wide open is five or more. On a bad morning a household asks for maybe 8 to 10 gallons a minute in bursts, not continuously.

Here is the part that surprises people: plenty of perfectly good wells produce less than that. A 5 gallon per minute well is normal and livable, because the well does not have to keep up with your peak, it has to keep up with your day. Between the water standing in the casing and the pressure tank, the system buffers the bursts. 5 gallons a minute over 24 hours is 7,200 gallons, far more than a household uses.

• Under 1 gallon per minute: hard living. Doable with storage, but it is a decision, not a detail, and it belongs in a purchase price.
• 1 to 3 gallons per minute: common in the foothills. Workable for a household that is not irrigating, and it wants a bigger pressure tank.
• 5 to 15 gallons per minute: comfortable for a house. Typical of decent valley wells.
• 20 and up: plenty, and interesting if you have livestock or acreage.

And the number the seller quotes is usually off the drilling report from 1987. That was a real measurement of a different water table, before the pump wore for thirty years. A starting point, not a finding.

Static level, pumping level, and drawdown

These three terms are what a flow test measures, and they are worth knowing before somebody hands you a report full of them.

Static water level

Where the water sits in the casing when the pump has been off long enough to settle. If your static level is 90 feet, the top 90 feet of the well is empty pipe. On its own it tells you almost nothing, which is why nobody should sell you a well on it.

Pumping water level

Where the water settles while the pump runs steadily. Turn a pump on and the level falls, because water comes out faster than the formation pushes it in. Eventually it either stabilizes, which is good, or keeps falling toward the pump, which is the finding.

Drawdown

The difference between the two. Small drawdown that stabilizes quickly means the formation feeds the well about as fast as you take water out. That is a strong well. Large drawdown that keeps going means you are emptying a hole faster than it refills. This is why the test takes time. A well that looks great at minute ten and is pumping air at minute forty is a well you would have bought on a short test.

Drawdown also decides where the pump gets set on a replacement, and it is why sizing a pump bigger than the well is a mistake rather than an upgrade. A pump that outruns the formation draws the water down to itself, loses the water cooling it, and burns.

Why this matters buying rural property here

On a rural parcel in Butte County, the well is infrastructure you are buying, and nobody in the transaction is responsible for telling you what it does.

The general home inspector will not tell you. Most run the taps, confirm water arrives, and note that the property has a well. Water arriving at a faucet for ninety seconds proves the pump turns on. It says nothing about yield, drawdown, water level, or whether the pump is a month from failing. A well can pass that check and still quit every August. The seller often genuinely does not know either. It has always worked, so the answer is "the well is fine," which is an honest answer to a question nobody asked properly.

The stakes are not subtle. If the well is low yield, that is a permanent condition of the property. If the pump is at the end of its life, that is $1,500 to $3,000 on a valley well and $2,800 to $5,500 on a deep foothill well, per the cost page. Both are worth vastly more than the test, and both are things you can only negotiate about before you own the place.

The geography splits the risk cleanly. Thermalito, Palermo, Gridley, and Biggs sit on shallow alluvial ground where wells are often 100 to 200 feet and yields tend to be reasonable. Berry Creek, Forbestown, Concow, Magalia, and Paradise are hard rock at 300 to 400 feet and beyond, where a well produces whatever a fracture in the granite gives it. Two neighbors on the same foothill road can have completely different wells, because they are drinking from different cracks in the same rock. There is no typical yield for a street up there, which is why the parcel has to be tested rather than assumed.

What a real inspection covers

If somebody quotes you a flow test, this is roughly what you should expect to be holding when it is done.

The flow test itself

Water pumped at a measured rate for a meaningful duration, with the water level tracked throughout, plus recovery after: how fast the well comes back once the pump is off. The output is a yield figure with a time attached and a drawdown curve showing whether the level stabilized or kept dropping. That curve is the finding. The single number is the headline.

Pump and wellhead

What the pump delivers against what it is rated for, amp draw against the motor's nameplate, and how it behaves under a sustained run. A pump losing performance is often the first sign of sand wear. At the wellhead: cap sealed, casing sound above grade, no obvious way for surface water to get in.

Tank and switch

Air charge checked against the switch cut-in, and the tank checked for waterlogging. This is where the common surprise lives. The house you are about to buy has been short cycling its pump for a year and nobody noticed, because water still came out. The pressure tank page covers what that does.

What it does not cover

Water quality is a lab test, not a pump contractor's inspection, and the contractors we refer do not perform it. What you get here is a mechanical picture: what the well makes, what the pump does, and what shape the equipment is in.

Water tables are dropping and some wells no longer reach

This is not an abstraction here, and it produces a call that sounds like a broken pump and is not one. The pattern is recognizable from the kitchen. Water runs fine for ten or fifteen minutes. Then it goes to spitting and air. Then, if the house leaves it alone for a few hours, it comes back and works fine again. Nothing is broken. The pump is doing what it was designed to do, and it is running out of water to do it with.

What changed is the water level, not the machinery. Drought years, more demand on the same groundwater, and a basin being drawn on harder than it recharges. The Vina and Wyandotte Creek subbasins are both under groundwater sustainability management for that reason. In a foothill hard rock well, a modest drop in the level is the difference between a working well and a well the pump can no longer reach.

Why this belongs on an inspection page rather than a repair page: a new pump does not fix it, because a new pump adds no water to a well. If the pump is hanging above the water, the options are lowering it, if there is well below to lower into, or changing how the house uses water. A flow test with a real drawdown curve tells you which conversation you are in. Guessing sells pumps to people whose old pump was fine. A well that tested at 8 gallons a minute in 1990 and 2 today is telling you a direction.

The well completion report, and how to pull it for free

This is free information most buyers never ask for, and it is the most useful thing you can bring to an inspection. When a well is drilled in California, the driller must file a well completion report, sometimes called a driller's log, with the state Department of Water Resources. Those reports are public. DWR publishes them through its Well Completion Report Map, a free online map searchable by location, with personal information redacted. Butte County's own well FAQ points residents to that same state map, so start there rather than with the county.

What is on it: the year it was drilled, total depth, casing size and material, where the perforations are, what the driller hit going down, the static level that day, and the yield measured when they finished.

It gives you a baseline. If the report says 380 feet in 1994 with a static level at 120, and a flow test today shows water at 260, you have learned something no amount of running taps would tell you. It also gives total depth, which determines whether lowering the pump is an option or whether it is already near the bottom.

Sometimes the report tells you the most by not existing. No report usually means the well predates the requirement or was never permitted. Neither is automatically a disaster, and older parcels here have plenty of both. But an unrecorded well with no documented depth is one where you know less than you should, and that belongs in the price. Pull it before the inspection: handing the contractor a driller's log turns a flow test into a comparison.