Well pump repair, and the pressure tank that is usually to blame

How a well system works

On a private well, four components have to cooperate. The pump lifts water from the well. The pressure tank stores a volume of water under air pressure so the pump does not have to run every time someone opens a tap. The pressure switch starts the pump when pressure falls to a cut-in point and stops it at a cut-out point. And the check valve stops water draining back down the well when the pump stops.

Understanding the tank's role is the key to diagnosing almost everything. The tank contains a bladder or diaphragm with compressed air on one side and water on the other. As water is drawn, the air expands, pressure falls, and eventually the switch starts the pump. That air cushion is what gives you a reservoir of usable water between pump starts.

When the air charge is lost or the bladder fails, there is no cushion. Pressure collapses the instant a tap opens, the switch calls the pump, pressure recovers immediately, the switch stops it, and the cycle repeats every few seconds. That is short cycling, and it is the single most common well problem there is. It also destroys pumps quickly, because a motor's wear is dominated by starts rather than run time.

So the diagnostic order matters: tank, then switch, then wiring and controls, then the pump itself. Pulling a submersible pump is a significant job, and it should never be the first assumption.

No water at all

Work through this in order before assuming the worst.

• Power. Check the breaker for the well pump, and the separate disconnect if there is one. Well pumps are frequently on their own circuit and a tripped breaker is a common cause. If it trips again immediately, stop, that indicates a fault rather than a nuisance trip.
• The pressure switch. Look at the gauge. Zero pressure with the pump not running suggests the switch is not calling, or has failed. A switch that has burnt contacts is a common and inexpensive failure.
• The pressure gauge itself, which can stick and give a false reading.
• Freezing, in winter. A well head, an exposed pipe run, or a pressure tank in an unheated space can all freeze: see pipe thawing.
• A tripped overload in the pump control box on some systems.
• The pump or the drop pipe. A failed motor, a broken wire down the well, a failed check valve letting water drain back, or a pump that has lost prime on a jet system.
• Water level. In a drought year or after heavy demand, the level can drop below the pump intake.

What to tell us when you call: whether the pump is audibly running, what the pressure gauge reads, whether the breaker has tripped, whether it happened suddenly or degraded, and whether it is deep well submersible or a jet pump in the basement. Those five facts shape what the technician brings.

Rapid cycling

If your pump starts and stops repeatedly while a tap runs, every few seconds rather than every minute or two. Stop using water where you reasonably can and get it looked at promptly. Each start is a burst of high current and mechanical stress, and a cycling pump can go from healthy to failed in a matter of weeks.

The causes, in order of likelihood:

Pressure tank has lost its air charge, or the bladder has ruptured so the tank is waterlogged. This accounts for the large majority of cycling complaints. Diagnosis is simple: tap the tank. A tank with a healthy charge sounds hollow in the upper portion and solid in the lower; a waterlogged tank sounds dull and solid throughout, and feels unexpectedly heavy.

Air charge set incorrectly. The pre-charge pressure should be set relative to the switch cut-in point, measured with the tank drained of water. Getting this wrong produces cycling even on a sound tank.

A failing pressure switch with a narrow or erratic differential.

A leaking check valve letting water drain back, so pressure falls immediately after the pump stops.

A plumbing leak somewhere in the system, which makes the pump start periodically with no water being used. If the pump runs when the house is asleep, you have a leak: see leak detection.

The pressure tank

Pressure tanks are consumable equipment. A bladder tank typically lasts somewhere between about eight and fifteen years, and the failure is progressive rather than sudden, the cushion diminishes, cycling increases, and pump wear accelerates before anything obviously breaks.

Sizing matters more than people expect. A larger tank means fewer pump starts for the same water use, and since starts are what wear out pumps, an adequately sized tank directly extends pump life. Undersized tanks are extremely common on older installations, and upgrading the tank at replacement time is usually the best value available in a well system.

What proper service looks like: checking the pre-charge with the tank drained, verifying the switch cut-in and cut-out settings, confirming the differential, checking the gauge, and inspecting the check valve. It is not a long job and it prevents the expensive one.

Worth noting that older galvanised tanks without a bladder rely on an air volume control to maintain the cushion, and those systems waterlog routinely. Replacing one with a modern bladder tank resolves a recurring problem permanently.

Pump types and replacement

Submersible pumps sit at depth in the well casing, pushing water up. They are the standard for deep wells, they are quiet, efficient and long-lived, often fifteen to twenty-five years, and when one fails, replacement means pulling the entire drop pipe and wiring from the well. That is a substantial operation requiring proper equipment, which is why the cheap failures should always be ruled out first.

Jet pumps sit above ground, usually in a basement, and draw water up by suction. Shallow-well single-pipe versions work to limited depths; deep-well two-pipe versions go further. They are easier and cheaper to access and service, noisier, less efficient, and they can lose prime, a jet pump that runs without delivering water has usually lost prime, and re-priming is a standard procedure.

When a submersible is replaced, it is worth doing everything at once while the well is open: the pump, the drop pipe if it is old, the wiring, the check valve, and a new well seal. Coming back to change a fifteen-dollar check valve later means pulling the pump again.

Sizing should be matched to the well's yield and the household's demand, not just to what came out. A pump that outpaces the well's recovery rate will draw the level down and run dry, which destroys it.

Falling yield and dry wells

Massachusetts sees genuine drought years, and a well that has always been adequate can become marginal.

The signs: water that runs muddy or sandy after heavy use; air spitting from taps; the pump running for long periods and pressure falling away during a shower; and recovery that takes hours rather than minutes after heavy demand.

The remedies depend on cause. Sometimes the pump can be lowered further into the casing where there is depth available. Sometimes the well can be deepened or hydrofractured to improve yield. Sometimes the answer is a storage tank with a booster arrangement, which buffers a low-yield well so the household experiences normal supply while the well recovers slowly. And occasionally the honest answer is a new well.

Running a pump dry is the thing to avoid at all costs. A low-water cutoff or a pump protection device is inexpensive insurance on any well that has ever run short, and it prevents the failure mode that turns a yield problem into a pump replacement.

Water quality and testing

On a private well nobody tests your water but you, and Massachusetts groundwater has some specific characteristics worth knowing about.

Common findings: iron and manganese, which stain fixtures and laundry and foul pumps and pipework; hardness, which scales appliances; low pH, which is common in New England and corrodes copper pipe from the inside; radon in water in parts of the state; arsenic and uranium in certain geologies; and bacterial contamination, particularly after flooding or well work.

Recommended practice is annual testing for bacteria and nitrate, and broader testing every few years or whenever taste, smell or appearance changes. Your local board of health can advise what is worth testing for in your area, since the risks are geologically specific.

Treatment follows testing rather than preceding it, installing equipment without knowing what you are treating is how people end up with the wrong system. See water treatment and filtration.

One plumbing note: low pH water quietly destroys copper supply piping, producing the pinhole leaks that eventually lead to repiping. If you are on a well with acidic water and you have copper pipe, neutralising treatment protects a much larger investment: see whole-home repiping.