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Question DetailsAsked on 12/29/2014

What is the holding tank for water coming from a cistern?

We have a cabin that pulls creek water into a cistern. A pump then pushes it to a holding tank "the label read Hydrocell". We believe this is the water that is pushed into the cabin for washing and toilet water. The cabin was built in 1969 and this is probably the original. I can't find anything in google to tell us what needs to be replaced.

Could it be a pressure tank? It's under the crawl space. We have to crawl under the cabin a prime the pump to get water. Now the water is coming out of this tank and we lost pressure in the cabin.

Do you think we will have start over and replace the pump and this Hydocell thing?

Thanks Cindi

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1 Answer


Sounds like this might be ruining your holiday at the cabin - sorry about that.

Without seeing your situation obviously I can't give a definitive answer, but let me lay out the major components I can think of for a typical system like yours, and maybe you can determine which ones you have and maybe what the problem is from there. Trace the flow of water, and at all possible points figure out by opening valves or turning pump on or off (do NOT let keep running if not getting water) to see a section is water filled or dry:

1) water source - creek in your case

2) conduit/pipe/canal to a holding tank/cistern/pond - maybe by gravity, maybe with a pump and pipe to pressure-pump or pull the water to the storage

3) depending on how high water tank/cistern is above the cabin, may flow by gravity to the cabin, with the pressure at the cabin equal to about 1/2 psi (pound per square inch) for every foot the cistern water level sits above the point of use. If not high enough to provide enough water pressure for use, then may have a pressure pump to pressurize the lines to and at the house. Can be one pump to fill cistern and another to pressurize house, can be one near creek/cistern to pull water in and pressurize both (if less than about 20' lift to pump from creek), or can be one pump at creek to pressurize entire system though usually not with a cistern, as an open cistern cannot be pressurized.

4) If you have a pump, to prevent it from constantly cycling on and off every time some water is used, there is usually a pressure control system - a limit switch the senses pressure at the pump outlet and turns the pump on at low pressure (maybe about 15-30 psi range) and off at high pressure (maybe 50-80 psi unless a high lift to the cistern/house), a pressure control tank (which may be the Hydrocell you are talking about) which absorbs any surges from the pump (especially if piston-type) and has air in the top 2/3 or so of it, so it pressures up (and pressurizes the air in the tank) till the pump shuts off, then uses that tank pressure (by the air expanding as water is used) to maintain system pressure between the high and low limit range till the system reaches the low-limit switch setting and the pump turns back on. If this tank fills with water (either by air bleeding off or the air diffusing in the water over time, or because the air/water separating bladder (may or may not have this) has ruptured, then the tank will be full of air and the pump will cycle on and off every time any measureable amount of water is used rather than just every maybe (depending on tank size) 5-30 gallons of use.

5) May also have a circulating pump or pipe to keep water running through the system so it does not freeze - either circulating through a small heater or a heat exchanger on the hot water heater, or even just continuously circulated back to the cistern to keep it moving so it does not freeze or go stagnant.

6) may also have a water purification system somwhere after pump and before use points. Hydrocell is a Siemens brandname for commercial oil/water, gas/water, and solids/water separator systems, but the smallest I find on their website is about 5 feet in diameter and about 10 feet long tank, so I doubt you have one of them for water pretreatment ahead of a water softener or reverse osmosis system. Otherwise, I can't find a Hydrocell brandname on the web which fits your case - may have been an old name for a pressure tank, or maybe for a sand filtration system. May also be a commercial tank used for commercial processes that was repurposed for your house as a home-built system - that is common.

Hydrocell is also a product name for activated carbon charcoal impurity absorber discs for humidifiers and air purifiers and such - I suppose someone could have put some of them in a tank as a do-it-yourself activated carbon filter system and stuck the label on the tank, but Air-O-Swiss does not make water purification units - just humidifiers and air cleaning products.

7) then distribution piping, possibly with a booster pump to provide household pressure if using gravity flow to that point, to your points of use.


Work through the flow path of the water and try to figure out what function each component serves, and whether the system is gravity flow or under pressure at that point - opening drain valves one at a time may help there (or use a hose-threaded pressure gauge) to determine which parts are gravity and which pressurized - that may help tell what part(s) are not working right. Also check for in-line valves that might have been shut off to prevent possible flooding if they leaked/froze when the cabin is unoccupied, and need to be opened to allow water flow.

You say you have to prime the pump - that implies either a lack of water coming to it (in which case it would stop providing water as soon as the priming water was pumped out), or it is has air coming to it than an air leak in a pipe with suction on it between the pump and the cistern (or cistern is dry), so it is sucking air instead of water (or both) - or a shut vavle between it and the cistern.

You say water is coming out of the tank - if leaking at a valve or hole in the tank, obviously that needs to be fixed. If located under the crawl space, assuming that is where the pump is too, then sounds like you have a pump pulling water from the cistern, and pressurizing the pressure tank as described above so the pump does not run continuously (or near so). Probably under the house to keep it from freezing - which implies if cabin is unheated when not in use, then system has to be totally drained when cabin is not in use ? If the tank is full of water the pump will cycle on and off basically every time you open a faucet or use more than a tiny bit of water (say more than a cupfull maybe).

If water is coming out of the tank at the top, at a bleed valve, then you probably (assuming it is a pressure tank and not a sand filter) need to turn off the pump, drain out the tank using the drain valve (with the top bleed valve open to let it fill with air) then shut the drain valve and the
bleed valve, and restart pump. Should take a while to pressurize the tank (several minutes) and you will likely have air in the house pipes that will need draining off too. May also shake some sediment and iron algae in the pipes and tank loose too, so may need several minutes of flow in all faucets/tub/shower/etc to clear up.

Obviously, if the tank is leaking through the side ofthe tank or at a fitting do not do this - take it out of service till replaced, because using a tank that is leaking may indicate critical corrosion, and the tank might violently fail.

That is about all I can offer cold - if you can draw a labelled sketch and post a photo or appropriate type file (TIFF and JPG) as I recall, (says when you go to download files at My Answer button for fle downloads), or maybe photo(s) of the components you can't figure out, maybe another contributor or I can help more. You can post response/photos/sketch image using the Answer This Question button right below your question - post photos using the leftmost yellow button right above the My Answer box. There are other yellow buttons for posting video and other files.

You may find a neighbor who knows what is what - especially if a neighbor has been used to watch the cabin when unoccupied. Ditto if owners/prior owners used a handyman or caretaker to maintain the cabin when not in use. Professionally, a Plumber is the best person to figure what is going on and what does what (and explain it to you), though if the problem is in a water treatment system he may or may not be able to get that working.

Answered 4 years ago by LCD

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