Bladder type Well X Trol Water Tank (C) Daniel Friedman Intermittent Loss of Water Pressure
How to Diagnose Water Pressure that Stops then Recovers on its Own

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Interimttent loss of building water pressure: diagnosis & cure. This article describes questions and answers from and to a homeowner who lost water pressure.

The basics process of diagnosis and the costs of the repair are explained. Consumer advice on saving money on well repair costs includes a review of the parts and labor costs of a typical well pump and pressure tank replacement case.

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How to diagnose loss of water pressure that later improves or returns "on its own"

When you lose water for some time period but later it returns we think immediately of the following possible explanations:

  • The well is being pumped "dry" and you're waiting for the well itself to recover water. With age however some wells deteriorate and deliver less and less water as their flow rate from the water table into the well diminishes. This occurs as minerals clog the cracks or passages through which water is entering the well.

    A well may be pumped "dry" - and the pump stops delivering water, or the well may be pumped down to a low flow rate - or a low recovery rate, which in some installations may permit the pump to continue to run but it will deliver water only at a reduced rate.

    Low Well Water well pipe tailpieces: Some wells that are known to have intermittent low water problems may be equipped with a special tailpiece on the water pick-up end of the well pipe precisely to prevent the well pump from becoming damaged when water level in the well drops too low.

    The tailpiece permits the in-well water pump to continue to run by recirculating well water within the pump but by halting delivery of water or slowing delivery of water to the building.
    See WATER PUMP LIFE EXPECTANCY where we describe these conditions and parts in more detail.

    This is a very likely cause of the intermittent loss of water or water pressure symptom.
  • Well pump motor is overheating: if a well pump motor is overheating for any reason (low voltage, bad start/run capacitor, damaged motor, damaged pump impeller parts, loss of water in the well, pump running dry) it may be a model that will turn itself off when too hot. A thermal sensor inside the pump motor housing handles this job.

    With the motor off for a cool-down period, the thermal sensor automatically resets and the pump will run again. Typically the "off" time is 15-20 minutes. If the pump on-off activity is erratic or very long, it could be that the problem is a bad thermal sensor switch.

    Note that other electric motors may have a thermal reset switch that is mechanical and "pops out" to show a red "reset button" that must be pushed back in manually. If the motor is still too hot, pushing the button won't work - the button won't stay in. See
  • Water pump hesitates before starting at end of water tank draw-down cycle -
    see How to Fine Tune the Pump Pressure Control Switch to the Water Tank.
  • If the pump runs, water pressure returns, but water pressure drops without explanation when the pump stops,
  • A pump is shutting down on thermal overload and you're waiting for it to cool down and automatically re-set its overload switch.

    If the well pump is visible in the building you can diagnose this condition:

  • If the pump keeps running and you have no water there is a problem with the well or well piping or foot valve in the well -- maybe. See contrasting cases after this list.

    Or on occasion, the pump could itself be damaged - its motor is spinning but the pump impeller is broken and the pump is not moving water.

    Explanation: If the well pump keeps running and you have no water it is also possible that the pump itself is defective, such as having broken internal parts so that the motor runs but the pump does not move water. But if the impeller blades in the pump are broken, the pump may spin but no water is moved inside the pump housing - the water supply system would have poor water pressure or it may have no water and never recover.

By contrast with cases where you lose but then recover water pressure in the building are cases where you lose and do not recover water pressure or flow:

You'd have either no water or only very low pump output no matter what conditions in the well.

  • Or the pump has lost its prime. If the water tank is empty the pump may need to be primed.
  • If the pump shuts itself off and is hot, it is off on thermal reset.
  • If the pump is in the well you can't see these conditions directly but an electrician or plumber can do some diagnosis from the building by noting the amperage draw on the pump circuit.

    If inside the well there is a leaky or broken water line rising from the pump, the pump could run but deliver less or no water to the building. If this defect is present, the system will not recover to normal operation on its own. In may cases the pump will deliver some water pressure but it is poor.

    If the well pipes come disconnected completely, the pump may run but no water will be delivered.

If the building water supply stops and takes minutes to hours to recover, you may have problem with the well flow rate. But the problem of lost water supply and pressure could be more mechanical: a bad well pump. The well pump, in turn, could have been damaged or hastened to the end of its life by a bad water pressure tank which has caused well pump short-cycling. Short cycling of the pump motor can burn up the pump relay control.

Readers of this document should also see Water pressure tanks - how to diagnose the need for air, how to add air, stop water pump short cycling to avoid damage - water storage water pressure tank safety. The illustration at left is courtesy of Carson Dunlop, Inc. in Toronto.


Continue reading at WATER PRESSURE INTERMITTENT LOSS or select a topic from the More Reading links shown below.

Or see WATER PRESSURE PROBLEM DIAGNOSIS TABLE in table format listing nearly every cause of water pressure loss or well pump problem identification, diagnosis, and repair.

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WATER PRESSURE STOPS, RETURNS at - online encyclopedia of building & environmental inspection, testing, diagnosis, repair, & problem prevention advice.

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