adding a water tank to well system

Joejoe1234December 3, 2012

Adding a water storage tank to an existing well system

Hello All,

This is my first post on this forum. I've tried searching for an answer but couldn't find what I was looking for.

I have a well that produces good quality water just not very much of it. A test back in March showed just over 1 gpm output. Today I ran a short hose wide open and I ran out of water after just 15 minutes. I measured the output of the hose with a couple of buckets and my watch and the output varied btw 7 and 8 gpm during that 15 minutes. The well is 80 feet deep and the pump is at about the 70' level inside the 6" casing. The pressure tank is 40 gallons (nominal) and it turns the pump on at 30 psi and off at 50 psi.

I'd like to add a 2000 gal above ground storage tank. I'd like to place it 50' from the well. The existing submersible pump is a half HP model that's wired with 12/3 cable on a 15amp/220v circuit.

After placing the tank I'd use the existing submersible pump to fill the tank. A second pump would be used in or outside of the storage tank to supply the house. I could also move the pressure tank next to the storage tank.

I can't find any pump company that will do it for me. they all want to redrill another well ($5,000.00) does anyone have an idea how to do this? Any suggestions are welcome.

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I'm not an expert but it seems you need two systems. One that fills the tank based on the volume of the tank and one that provides pressure to the house. So the well pump would come on when the volume in the tank falls below a certain level and shuts off when it reaches another level (opposite but not dissimilar to how a sump pump operates). A pressure sensors turns on a pump to provide water to the house, with a pressure tank making up for any "lag."

So, for example, when you take a shower a pump moves water from the tank to the house. After, say, 5 minutes when you are done with the shower, that pump shuts off. While you are taking the shower and for some period of time afterwards, the well pump refills the tank.

    Bookmark   December 3, 2012 at 11:32PM
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try looking under water tower

Here is a link that might be useful: water tower

    Bookmark   December 4, 2012 at 12:51PM
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Your idea is workable. It will be necessary to cycle the well pump at intervals that will not empty the well and have that pump running while dry which will ruin the pump. Your capital outlay will be considerable and operating costs will be considerably higher with two pumps. Some sources indicate that the typical household uses about 200 gallons per day, obviously not all at once, so your present system may work well enough as it is. An alternative is to deepen the existing well. We are not told the size (diameter) of the existing well. A 6" well holds about 1 1/2 gallons per foot of water depth, so an extra 100 feet would store about 150 gallons. Additionally, while that is being exhausted, more is coming in at the rate of a gallon per minute. I have a well 610 feet deep with an inflow of 1 gallon per minute, static level of about 70 feet. At times it has supplied 5 households without problems.
For deeper and at replacement, I suggest a 240 volt pump. For a given horsepower, the voltage drop in the conductors will be just 1/4 that of the 120 volt system.

    Bookmark   December 4, 2012 at 1:00PM
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Two questions come to mind. Won't water in the storage tank support microbial growth? If so, what needs to be done about that? Isn't 2000 gallons a awful lot for one typical house if bus_driver's number is correct and a typical household uses 200 gallons/day?

Why not install a larger pressure tank and a slow pump?

    Bookmark   December 4, 2012 at 2:35PM
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"Won't water in the storage tank support microbial growth?"
A good question. But consider that the water in the well is just sitting there until some portion of it is pumped out. The pump is often considerably below the surface of the water. I suspect that much of the "microbial growth", if any, is simply not harmful to people. And it would be as prevalent in the well as in the tank. I have lived much of my life on untested and untreated well water- including several years when the water was drawn up with a bucket and rope.
My wife's Mother is approaching her 100th birthday and never had any water supply other than a spring or a well. Her water supply comes from my well now. And wisely or not, this well has not been tested.

This post was edited by bus_driver on Tue, Dec 4, 12 at 21:35

    Bookmark   December 4, 2012 at 4:01PM
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Bus_driver, all good points. I thought of most of that and shrugged. Not being a well or pump expert, I can't really comment beyond the fact that a lot changes after the water if pumped out of an open or closed well. Important changes that I can think of are temperature, dissolved gasses and exposure to surface contamination.. With a pressure tank, the dissolved gasses and exposure to surface contamination won't change much until the water hits the faucets. In an open tank, it will. If I were contemplating a change like the OP, I would do considerable research on the conventions involved in construction and use of such a cistern.

    Bookmark   December 4, 2012 at 4:35PM
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People in NZ and Australia use tank water, collected from rainwater exclusively in some places.

Theoretically, it should probably be treated and the tanks cleaned periodically, in practice, few do and they're fine.

They've done a lot to improve the water going in, with diverter systems that allow the eavestrough to be rinsed out before the water goes into the tank, things like that.

Presumably OP is in a climate where freezing won't be an issue.

    Bookmark   December 7, 2012 at 1:19AM
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