Adding a water storage tank to an existing well system

22 years ago

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. This ended up longer than I wanted but I've tried to anticipate some of your questions about my system.

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. When the well hasn't been used for a few hours the water level will trickle out of the top of the well casing if I remove the cap. I did the test with the well cap off so I could time how long it took for the water level to get back to the top. After waiting 90 minutes I still couldn't see the water level inside the well although I could hear a trickle of the water entering the casing somewhere down there. BTW, I shut off the breaker while waiting for the casing to refill since I didn't want the pump to suck any more air. The well is 80 feet deep and the pump is at about the 70' level inside the 6" casing. Ground level at the well is about 50' lower then ground level where the pressure tank is inside my house. 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 underground storage tank. I'd like to place it down by the well if possible. The well is about 500' from the house and the existing pressure tank and pump control relay. The existing submersible pump is a half HP model that's wired with 12/3 cable on a 15amp/220v circuit. Is there any way to put the tank down there without running new cable to the tank? Trenching runs about $1 a foot around here so I'd like to avoid it if possible.

After placing the tank down by the well 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 down to the pump house if that helps my situation. My dilemma is that there is no power down at the pump house except the existing cable that goes to the well pump. I believe that a 12 gauge circuit usually supports a 20 amp circuit but I suppose mine is 15 amp due to the distance. I haven't measured voltage drop yet but will soon. If voltage drop isn't excessive could I replace the 15 amp breaker with a 20 amp breaker? If so I was thinking I could bypass the pressure tank switch so the wire to the pump is always hot and then control the sub pump with the relocated pressure tank/switch down at the pump house. I'm worried that the circuit wont support both pumps but I could wire in a relay easily enough to shut off the sub pump whenever the storage tank pump is running. I would have the sub pump run until just before it sucked air and then have it shut off until the water reached an adequate level to resume filling the tank.

Any suggestions are welcome. I believe that I will end up deepening the well next year so at some point I'll have to trench in heavier gauge cable to support the deeper pump but for now drilling and trenching is not an option.

Thanks,

Hugh

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Comments (5)

DynaMark
21 years ago
last modified: 11 years ago
Sounds very complicated. I'm on a well too which is about 200 feet deep. I know that because I had the motor replaced a few years ago.
Don't know why your output is so low but if the well is not filling fast enough what good is an extra tank ?
Some thoughts. It may sound silly but you could install a pool and use it as a water source by trucking in the water. You could also install the 2k gallon tank as you mention and also have the water trucked in. You could install cisterns and catch the roof runoff in underground storage. I knew a guy in New Hampshire whose well at 300 feet ran dry and he had to extend it to 600 feet to get a sufficient supply of water. Good luck.
irri_guy
21 years ago
last modified: 11 years ago
I just happened to come by this forum for maybe the second time in several months. This gets into several issues that are about technology. There are several very sharp people who address these sorts of issues daily, but on other forums in this group.

See "irrigation" which is under "professional topics", and especially "plumbing" and "electrical wiring" under "That Home Site" (linked). I suggest you repost this on the electrical wiring forum. I promise you will get useful responses quickly. It will be better to get others involved from the beginning.

Now, a bit on your questions. Number twelve would not handle a second pump at 500 ft, you are limited to one 1/2 HP as it stands. Voltage drop is already an issue at the 3% voltage drop standard, probably okay at the 5% overall drop standard. This is based on a nominal 4.9 amp draw for the 1/2 HP.

Alternating pumps would be technically possible but probably not the best solution. Could the storage tank be located near the house? It would be simpler and probably better to have independent power to the second pump. Output from a good 1/2 HP sub in a tank at the lower elevation would be about 9 gpm at 50 ft. + 50 psi. That might be a little small.

I also wonder if the storage tank could be smaller. What sort of flow and volume demands would you like to serve? What is the time frame? Answers to those questions will influence the choices for the second system.

Here is a link that might be useful: see plumbing & electrical forums
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irishcowboy
12 years ago
last modified: 11 years ago
I also have a similar problem as do many other people here do. My question is how does a person set up the large tank in the system? Would you set it up like a pressure tank is set up with a float valve to close off the supply from the pressure tanks?

Ours currently has 2 pressure tanks, the second one helped our but still have a problem of air locking / favitating due to pump out faster then water can leach back in to the well casement. We have a60 foot x 6 inch reservoir. The pump is at the bottom. We also found by chocking down the out put of the pump using a ball valve allows the pump to run longer . and we chock down the flow between the pressure tanks to where it seeps into the second tank ( which helps but we still have an issue doing laundry. We can only run one fixture at a time. Plenty of water just slow.

WE acquired a 1500 gallon tank. Which has a single inlet/outlet at the bottom. We could drill a hole at the top but do not wish to damage the integrity of the tank wall if it is not needed.

What is the best way of incorporating this into the system? It will be placed close to the house under shade trees to keep it out of the direct sun. Placed on a mound as to use gravity as much as possible......

Any ideas most welcome....

Mike.
irishcowboy
12 years ago
last modified: 11 years ago
I also have a similar problem as do many other people here do. My question is how does a person set up the large tank in the system? Would you set it up like a pressure tank is set up with a float valve to close off the supply from the pressure tanks?

Ours currently has 2 pressure tanks, the second one helped our but still have a problem of air locking / favitating due to pump out faster then water can leach back in to the well casement. We have a60 foot x 6 inch reservoir. The pump is at the bottom. We also found by chocking down the out put of the pump using a ball valve allows the pump to run longer . and we chock down the flow between the pressure tanks to where it seeps into the second tank ( which helps but we still have an issue doing laundry. We can only run one fixture at a time. Plenty of water just slow.

WE acquired a 1500 gallon tank. Which has a single inlet/outlet at the bottom. We could drill a hole at the top but do not wish to damage the integrity of the tank wall if it is not needed.

What is the best way of incorporating this into the system? It will be placed close to the house under shade trees to keep it out of the direct sun. Placed on a mound as to use gravity as much as possible......

Any ideas most welcome....

Mike.
HU-170588634
4 years ago
I have a similar problem. I put a pump protector in place of the motor control box in basement. ($259 on Amazon) This turns off the pump for a time (30 minutes to an hour -programmable) when the well level is too low. I am getting a 200 gallon tank installed in the basement to accept water from the well. A simple level sense will control when the pump is turned on. The tank is not pressurized.

A second pump moves water from the 200 gallon holding tank to the existing 36 gallon pressure tank. Your plumber should understand how to do this.

Some of the mansions being built in Maryland are required to have this arrangement to supply a sprinkler system. It is a standard installation.

Adding a water storage tank to an existing well system

Comments (5)

DynaMark

irri_guy

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irishcowboy

irishcowboy

HU-170588634

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