How to Diagnose & Repair Intermittent Lack of Water Pressure from Wells or Municipal Supply InspectAPedia® -
How to diagnose intermittent or cycling bad water pressure in a building
Guide to diagnosing water pressure that comes and goes, municipal or well water
How to diagnose loss of water pressure or loss of water in a building
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This article describes how to diagnose periodic or intermittent loss of water pressure from municipal water supply piping and how to diagnose periodic or intermittent loss of water pressure from a private well.
The 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.
If the building water supply stops and takes minutes to hours to recover, the municipal water system may have work going on outside of your building, or if you're supplied by a private well, you may have problem with the well flow rate. But the problem of lost water supply and pressure could be
more mechanical and may be due to a problem right in your building itself.
MUNICIPAL WATER PRESSURE DIAGNOSIS: If your water is from a municipal supply and the pressure or flow seem to vary or start and stop
Variation in supply pressure: There could be variation in water pressure supplied by the municipality - check with your neighbors and your water department. You can install a pressure valve at your water entry main and watch for variations in its reading when you're not even running water in your building. This is a likely cause but it's unlikely to continue for days or weeks.
Clogged piping or multiple users: There could be a problem with poor water pressure due to clogged pipes combined with other people in the building using water at the same time. This is a likely cause, it could continue for years, and it would correlate with the presence or absence of various building occupants and their water use. See Water pipe clog diagnosis for a step by step diagnostic guide to this cause of bad water pressure.
Bad water pressure regulator: You could have a problem with your water regulator but it's unlikely that this would cause varying pressure. If you have this rare problem a plumber can change out the pressure regulator. See WATER PRESSURE REGULATOR ADJUST
No municipal water pressure at all: see No Water Pressure for a step by step diagnostic guide.
WELL WATER PRESSURE DIAGNOSIS: If your water is provided by a private well and the pressure or flow seem to vary or start and stop
When you lose water pressure or lose all water supply for some time period but water pressure later returns or improves, check the possible explanations outlined just below.
On the other hand, if you lose and do not recover water pressure in the building see Diagnosis of Loss of Water Pressure which Does Not Recover on its Own.
First Check the Basics: Has someone partially shut off the main or some other water supply valve? Is there an obvious burst pipe? Is the water pump running at all? Is the electricity turned on for the well pump? See our detailed diagnostic list at: WATER PRESSURE LOSS DIAGNOSIS GUIDE
Is there water in the well? If so, how much water is in the well? Is the well 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. You might need to find the well, open the well cap, and use a light and measuring tape, or possibly a combination of string and float to find the amount of water in the well when it is at rest. Problems with well casing or well flow and recovery - loss of ground water and many other causes of loss of water are discussed at our comprehensive article: WATER PRESSURE LOSS DIAGNOSIS GUIDE See:
Are the well pump controls turning on the pump properly? A pressure switch senses pressure drop in the water tank and either turns on the well pump directly or it turns on a heavy duty relay that turns on the well pump. The detailed, step by step procedure for inspecting and adjusting the water pressure control switch is discussed in detail at WATER PUMP PRESSURE CONTROL ADJUSTMENT
Is the well pump actually running? If the water pump is above ground, you will hear the pump motor running; if the pump is a submersible unit in the well, you won't hear the pump run, but your plumber or electrician can confirm that wiring to the pump is intact, that current is being delivered to the pump.
Is the water pump is shutting down on thermal overload and you're waiting for it to cool down and automatically re-set it's overload switch. (Other electrical motors including on some pumps have a reset switch which must be re-set manually by pressing the "popped out" red button down. If the pump is visible in the building you can diagnose this condition:
If the pump keeps running and you have no water (TURN OFF THE PUMP RIGHT AWAY in this case) there is
a problem with the well pump itself, such as internal well pump damage, broken vane, mineral clogging, in which case the pup motor may run but pump does not deliver water (this will not normally give intermittent water flow, the problem will be static)
a problem with the water well (no water or insufficient water)
a problem with the foot valve in the well or some other check valve in the system - this could give an intermittent water loss if the valve is sticking open on occasion and the pump loses prime. See WELL PIPING FOOT VALVES
a problem with the well piping between the bottom of the well, foot valve or submersible pump, and piping entering the water pressure tank, such as a burst or leaky pipe - (this will not normally give intermittent water flow, the problem will be static) SeeWATER SUPPLY & DRAIN PIPING.
a problem with a plumbing valve that is closed in the piping system. If a water valve is closed between the well pump and the pressure tank, the water pump will cycle on and off very quickly - and can be damaged - turn off the pump. We've found this problem happening when someone used the built-in water shutoff valve on a cartridge type water filter. The filter was replaced and the pump turned back on but the pump kept switching on and off rapidly - the owner had forgotten to turn the built-in water shutoff valve back to the "on" position. (this will not give intermittent water flow, the problem will be static)
See contrasting cases after this list. Turn off the water pump immediately so that you don't burn out the motor. Some water pumps depend on having water inside the pumping mechanism to avoid wear or overheating.
If the pump shuts itself off and is hot, it's off on thermal reset. Feel the pump motor. Read the operating temperature range expected by the pump manufacturer - this data is usually on a label affixed to the pump motor.
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.
Is water being delivered to the building when the pump runs? See the same questions as at step 8 above.
Is there a problem with the water pressure tank itself, such as loss of air in a bladderless steel water tank, or a tank bladder that is damaged or is sticking to itself, preventing water from entering the tank? Check these articles
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.
These pages are chapters of our comprehensive article: WATER PRESSURE LOSS DIAGNOSIS GUIDE. Contact Us with suggestions and your own experience as that may help us help others diagnose water delivery problems.
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Thanks to reader Vincent Madison 03/02/2010 for email questioning that suggested expansions in this discussion of variations in available water supply at buildings.
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