well yield

[mike223]

I have a question for the group. I have drilled a well on some property and it is yielding 5 gpm. Is this enough to support a household? My driller assures me that it is. Any comments are appreciated. The driller also told me that for any type of irrigation I will need a 1500 G holding tank, which I think is probably true. I am in the process of purchasing this property, but I have a contingency that the well has to produce sufficient water quantity and quality for household use, or the deal is off. Thanks.

 

[valleydweller1]

I have a 10gpm well that supplies two houses. Based on that, yes, a 5gpm well will supply a household. A large pressure tank will help as well.

As for your 1500 gallon tank, basic math shows that it will take 5 hours to refill (assuming you don't use any water in your house during that time). I think it would be reasonable to draw down your irrigation tank and let it refill from the well at night.

 

[Highbeam]

Yep, sufficient for a single family home. Irrigating big areas, or extra uses may overload it.

The real question is whether the 5 gpm is consistent year round.

 

[bugstruck]

Mike,

5 gpm is the minimum preferred for household use in my book. Many make do on less. Generally, with enough reserve depth below the water source it should work fine. Now if you start irrigation at over 3 or 4 gallons per minute, plus the house it could get rather tight. Most hoses, faucets, etc. put out something on the order of say 3-4 gpm at 35 to 40 psi. So theoretically, you can turn a single device on and run around the clock and not lower the water level in that well. You have well over 5,000 gallons to waste in a 24 hour period, after all household use. That 1500 gallon holding tank may not be required if you can moderate the flow rate to say 2 gpm or less on the irrigation. I would have a large primary house storage tank though, to keep the pump on/off frequency down.

I don't recall the reserve gallons per ft. of depth but you can look that up for various size (diameter) wells. Usually 6" here. You have to take the total well depth, deduct the pump depth off the bottom, and deduct the distance from the top of the well to the top of the water column. That gives you the net standing reserve water column height. Then apply the column height to the volume per foot of water, for your well diameter. That will give you the minimum total gallons of reserve.

Make sure they did at least a (4) hour pump test. Most areas require a 4-6 hour test. I wouldn't be to concerned about 5 gpm. Sure 15 would be better, but in Maryland I'm guessing 7 to 9 gpm is average. In my County you need 1 GPM and a 500 gallon reserve as the technical minimums. They are inadequate for any real irrigation though.

HTH

 

[Farwell]

My well puts out 10 gallons a minute and I find that this is ample output for my place. The only problem I have is if the washing machine is drawing water my sprinklers slow down. I could probably solve this problem if I had a bigger pressure tank. 5 gallons a minute is less than I would want. !0 gallons a minute is the least that I would accept.
If I was not in cold country I would put in a low volume, low voltage pump and a 2000 gallon holding tank. Researched this on the Internet once and it sounded practical and economical. The pump could be powered by solar.
You probably should do some local research on water tables and other wells in your area. Wells are usually regulated by some local agency, contact them for advice.
Farwell

 

[mike223]

Right now this is the estimated output by the driller. The pump test will be done next week. This is a new well, so I can't say whether it will last or not, but evidently this yield is about average for this area of TN. Most of the people around here are on developed springs, which also have about the same or less output than this well. There are two springs on the property, which were flowing at about 2-3 gpm in mid August, when evaluated, and due to the long distance from where the house will be (1200') would have cost $12000 to $15000 to develop. Pipe/trenching costs big dinero. The well was the most cost effective option, but the biggest gamble, i.e. "dry hole". At least it wasn't that. County water is available, but it would take 3500' of 6" main to bring it to my doorstep, and at $10/ft plus engineering drawings that was not an option at all. We're keeping our finger crossed that it will be at least 5 gpm and have a constant flow. We don't close until January, so I will pay to have it tested again prior to closing.

 

[Highbeam]

Gotta tell you that mucho dinero needn't be spent to run water lines. A whole lot of 2"-1.5" PVC or PE water line can be had for little dinero, the trencher rental in my area is only a couple hundred per day for a nice heavy unit that will put a trench down the minimum couple or more feet. I wouldn't be afraid of running 1200' of water line big enough for a single home.

Well at least you have a well, you can supplement it later with the springs or even the county main if it becomes available closer. 6" water main isn't needed to your home but the extension probably needs to be that big in the street.

 

[valleydweller1]

</font><font color="blue" class="small">( There are two springs on the property, which were flowing at about 2-3 gpm in mid August, when evaluated, and due to the long distance from where the house will be (1200') would have cost $12000 to $15000 to develop. )</font>

Hmm...

$3000 for pipe and fittings, that would leave you with $9-12000 for a down on a new BX23, and you could do the trenching yourself.

 

[MadReferee]

How deep is the well in the ground?

What is the static level of the water in the well?

My well gives just a little over 1 gpm recovery. We have been using it for over 25 years and have never ran it dry with a family of five. However the 6" well is 360 ft deep and the static level is almost to the top. That translates to over 500 gallons of standing water reserve.

You might want to cruise over to CBN and check out their Water forum. This topic has been discussed there in detail.

 

[x585guy]

I have a drilled well on property that only yeilds 2 gpm. If I remember correctly, that is just enough for state of NH's min. standards.The well is however 365 feet deep which gives me several hundred gallons in reserve. The only time I ever came close to running out is when I had both outside faucets on watering the lawn. I fell asleep and when I awoke 3 hrs. later, the water was turning brown. I have had no problems since that time but I don't think it could handle filling up an above ground swimming pool. I would love to have 5 gpm. You should have no problems with that amount coming from your well on your new property. Good luck!!!