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Question DetailsAsked on 3/9/2018

Low water pressure in pressure well tank after a freeze...HELP!

We have an 86 gal Water Worker pressurized well tank that was working fine. We shut the well pump off and drained the water from taps. we were gone for a week during a hard freeze (no heat at all in the house during our absence), came back, turned everything back on and now have little or no water pressure. pressure tank gauge reads 41 psi currently, which is within recommended range. kitchen faucet has VERY little pressure, bathroom faucet better, but still weak and runs down quickly and outdoor bib barely a trickle when it used to gush. wondering if there could be an ice block in the tank? we opened taps after shutting down the pump to drain lines, but run out was super quick (which is weird cause the tank holds a ton) we did not close off the water where it comes into the house. i can't come up with any other reason...thinking about putting an electric heater in the utility room and letting it run for awhile? any ideas out there?

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You do not say if pump and pressure tank are indoors or outside - I am going to assume outdoors, adjust my comments as applicable if inside now-heated house.

Simplest solution - since you say you have a trickle of water, turn on (with supervision - of each if house has not been up to temp for some time, but especially of lowest elevation drain in house, in case of sewer pipe/line freezeup) several faucets and let them run as full flow as they will - if ice is the problem, within 15-30 minutes you should see an increase in flow (this assuming pump is turned back on), though may take several hours flow to totally thaw out the blockage. Of course, if your well has limited output, and does not have a functioning low-level shutoff for the pump (as all should), then do not run so long oyou run the pump dry - run for a bit, let well refill for an hour or so, then run water again.

I would not use a heater on the tank, because you are assuming its overpressure relief valve will work if the outflow from the tank is blocked - not a good assumption especially if it may still be frozen, and you do NOT want to blow up a pressure tank. Probably heating the utility room to not over about 45 degrees for gradual thawing (and check frequently for any burst pipes/leaking joints) is probably OK - but I would NOT heat it way up quickly, and personally I would check (exercise) the overpressure valve first to be sure it will open freely and let excess pressure out. If air comes out vigorously, not only does that comfirm it works but also that the pressure gage is probably not lying. If water comes out forcefully then gage is probably right but tank is full of water and should be re-aired per instructions.

Most well pumps have a line drain valve at the pump on the outgoing side (for above-ground pumps) or where the pump line comes into the wellhouse/utility room (usually where it goes from plastic well droptube to metal pipe), located BEFORE the pressure tank - if you open that and water comes out full force (with pump power on) then you have a blockage between there and the house - try any other drains along the way (including the pressure tank assuming it has a bottom drain, or one close by) should isolate the blockage location.

Holding the bottom drain (not the overpressure valve, as that will bleed your air off) open for some seconds would also tell you if the line is thawed from the well to the tank if it keeps flowing full flow and causes the pump to kick on as the pressure drops (should only take not many seconds fo flow). If nothing comes out tank is frozen or line betweenthe well and there is frozen.

BTW - you said the tank "holds a ton" of water but the pressure drops off real quick in the lines when you open a faucet - ignoring the possibility the tank is lower elevation than the faucets so water in it and the lines would not flow uphill to the faucet when you turn it on (normal situation), actually the tank should have very little water in it. it's purpose is to hold air, to act as a surge tank, with the pump compressing the air in it before the pump shuts off, so when you first use a bit of water the tank provides the pressure (say manybe 4w5-70 psi typically) in the line - with the pump kicking back on only after the pressure in the tank drops off quite a bit (typically to maybe 20-40 psi). This keeps the pump from constantly cycling on and off if say someone say just washes their hands or fills a glass of water or such - the pump only comes on with significant water demand. BTW - if the tank fills with water then the pump will short-cyle - running every time any water is used, and should be drained and refilled with air per instructions. Can commonly be recharged either by draining it out, or by adding air through a schrader (bicycle tire type) valve at the top. Latter is usually recommended because many times just draining out and then lettering the water pressure refill the tank results in more water in the tank than it should have.

One other thing on the rapid line depressurization when you open a faucet - that pressure may also be not from the pump at all - it could be because you have a still-growing ice plug in the line, constantly pressuring the line up as the blockage extends through the pipe. If that is the case, once having turned a faucet on (so letting the pressure drop off quickly), if you do that again in a minute or so the pressure will not rebuild that fast if from the line freezing - so if it pressures up again quickly then you have pressure making it into the system from the pump, pressure tank, or an elevated storage tank if you have that.

One thing I have seen on pressure tanks which froze - sometimes the freezing water will overpressure the diaphragm inside the tank ( if a diaphragm type) and the diaphragm can settle on the outlet opening in the bottom of the tank - blocking the water from passing through the tank. This would be only for types where the water passes through the tank (not unusual for outdoor and well tanks as it helps flush out sediment which can block the valve and reduces the tendency to freeze). Not applicable to single-connection tanks though could block the pressure in the tank from your line - evidently not in your case since you have 41 psi.

BTW - on that - if you have 41 psi in the tank but open faucets "downstream", then you have to have a blockage at the tank outlet or downstream - likely a frozen exposed or shallow pipe.

One other possibility - if you have a pressure regulator and/or backflow preventer in the house (usually right where the pipe enters the house), if the outside lines overpressured because of freezing, that could have damaged one or both of them and caused it to basically but not entirely close off. Overpressurizing can sometimes do this - some models have a reset mechanism to open it back up manually, some not.

You could (assuming threaded rather than soldered connections) turn pump off and drain off outside pressure at any available drain valve at the pump or pressure tank (or shut off incoming water line main valve if you have one), then disconnect the incoming line first at the outlet of the pressure regulator/backflow preventer. If water comes out full flow when pump is on/main water shutoff vlave is partly opened, the problem is on the house side of there. If essentially no flow when pump/valve are on/open, then shut off valve again and undo pipe at the inlet side of the regulator/backflow preventer. If flow there when main valve is opened up, then the problem is at that regulator/preventer.

Answered 2 years ago by LCD

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