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  #1  
Old 07-26-2005, 07:01 PM
CrazyFoo CrazyFoo is offline
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Drilled Wells, How many GPM?

Water & Well experts as well as coutntry folk, I need your help.

My wife & I put a offer on a new home being built in the country (under construction now) and the well report shows 5 gallons per minute.

The test and date of report was done in January when it was freezing temperatures.

My wife is thinking about canceling the deal because she believes 5 GPM is not enough, and this is a borderline flow rate.
We have seen ads for other homes showing 10-15 GPM, and this is the cause of her aprehension.

Is 5 gallons per minute sufficient, or is this a big mistake on our part?

She respects the opinions of the people on this site, as do I, so please help us put this matter to rest.

The well is drilled well and 90 feet deep.
Only 2 of us will live in the house.

Thanks in advance
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  #2  
Old 07-26-2005, 07:29 PM
MC$E MC$E is online now
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My parents have a well that puts out 3 GPM, and they get by, but could use a little more. Here is a web page that shows how much typical appliances use.

http://www.inspect-ny.com/septic/wateruse.htm

Keep in mind that it will flow back in at a constant 5 GPM, while you will only be drawing it out intermittently. You can also figure the volume of the column of water from the pump input up to the water table, if you know the diameter of the well casing. This will be the amount you can use above the 5 GPM refresh rate.
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  #3  
Old 07-27-2005, 05:58 AM
CrazyFoo CrazyFoo is offline
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Thanks for that!

Anyone else have any thoughts on the matter?

Regards
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  #4  
Old 07-27-2005, 09:23 AM
Balthisar Balthisar is offline
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Yeah, consider a cistern. Here's kind of a description that I recently posted on another thread. In my description, the cistern is for dealing with droughts. But because of the pump and resevoir system, you get fantastic water pressure and flow volume. Good example: there's so much volume with the system that I would exhaust the 30 gallon hot water tank in a single shower with a regular, old fashioned showed head. I had to wait for a trip back to Michigan to buy one of those "crappy" low-flow shower heads that are ubiquitous back home in order to enjoy my shower. I still get "too much" water in the shower. And this is in a desert/drought climate with active rationing!
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  #5  
Old 07-27-2005, 10:07 AM
dauerbach dauerbach is offline
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I can't imagine 5 gpm being insufficient for anything. In Baltimore County, Maryland the legal minimum is 1 gpm, and million dollar homes are going up on those lots. Unfortunately, 1 gpm is not actually enough for peak use. Our well is 5 gpm, and even when all six of us are at home there has never been any problem at all. Remember that there is considerable standing water in the well tubing, and you will most likely have a pressurized holding tank, and taking all this together makes it highly unlikely you will ever have any water shortage at all.
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  #6  
Old 07-27-2005, 05:09 PM
MC$E MC$E is online now
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Quote:
Originally Posted by dauerbach
I can't imagine 5 gpm being insufficient for anything. In Baltimore County, Maryland the legal minimum is 1 gpm, and million dollar homes are going up on those lots. Unfortunately, 1 gpm is not actually enough for peak use. Our well is 5 gpm, and even when all six of us are at home there has never been any problem at all. Remember that there is considerable standing water in the well tubing, and you will most likely have a pressurized holding tank, and taking all this together makes it highly unlikely you will ever have any water shortage at all.
Now that's something. My parents that I mentioned in the post above live in Baltimore County, Maryland also.
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  #7  
Old 07-27-2005, 05:35 PM
dauerbach dauerbach is offline
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Just to expound a little bit more on peak useage, the gpm is irrelevent most of the time because all people are doing is flushing the toilet or washing their hands. At night however, we have showers or baths, dishwashers, and washing machines. You might use 250 gallons in a peak hour. 5 gpm is 300 gallons in the same period. Even if you didn't have water stored in the well casing, stored in the hot water heater, and in the constant pressure tank you could get by during that one hour with just a little timing.
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  #8  
Old 07-27-2005, 06:46 PM
Gary "Wombat" Robson Gary "Wombat" Robson is offline
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Your 5gpm well should be adequate unless you're putting in a serious irrigation system for the lawn & garden and running it while taking a shower and running the dishwasher.

Plan ahead, though. If more homes may be going in nearby, then that will be a greater draw on the water table. Similarly, in some areas the water table is considerably higher in January than in the middle of the summer.

I'd recommend a cistern, as Balthisar suggested, or at least an oversized pressure tank. I had a 30-gallon pressure tank on my old well, and replaced it with an 80-gallon unit. It made all the difference in the world.
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  #9  
Old 07-27-2005, 07:37 PM
bouv bouv is offline
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Am I the only on e who read the title as:

"David Wells, how many GPM?"

I was seriously thinking what pitching statistic could possibly be represented by GPM.
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  #10  
Old 07-27-2005, 07:46 PM
Jonathan Chance Jonathan Chance is offline
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A good storage tank could do you, though. We got by for 7 years on well water with one at about 2-3 GPM. Had trouble with the gear sometimes but never with the flow rate or water availability.

WARNING THOUGH!

If this 'new house' is in a development that has many homes going up...

Note that, even though the homes are pulling from the same underground water source, they generally test each one at different times. So there's a possibility that when all those homes are up and functioning your actual draw could be significantly less than 5 GPM.

Also note: if you're relying on an electric pump for your water pressure when your power goes so does your water. Not fun.
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  #11  
Old 07-27-2005, 08:10 PM
CrazyFoo CrazyFoo is offline
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I appreciate the feed back everyone, you make some points I never considered.

The property is located on an old rural road which consists of 4-5 homes on 5-10 acre lots, and a few farms 100+ acres. There are no immediate plans to make this a thriving subdivision.

I want to look into somehow getting solar panels as a back up power source for the pump and I will definitly look into a bigger tank.

I'm not crazy about the idea of a cictern because I've read how they can be contaminated, however if it comes to that it will leave us little choice.

Thanks again for the helpful replies.
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  #12  
Old 07-28-2005, 10:06 AM
dauerbach dauerbach is offline
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Just note that you have a shallow well in an agricultural environment. You may well have a problem with nitrates. Be sure to check that out before you buy. Nitrates are not necessarily a problem except in infants, but I wouldn't want water with alot of them. If everything else about the house is fine you could always invest in a reverse osmosis system for drinking water.
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  #13  
Old 07-28-2005, 10:08 AM
dauerbach dauerbach is offline
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This site: http://www.health.state.mn.us/divs/e...s/nitrate.html has some very good and succinct information on relatively shallow wells in agricultural areas.
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  #14  
Old 07-28-2005, 01:05 PM
The Composer The Composer is offline
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In the summer of 1986, we had a bored well to run dry during a drought. A new drilled well replaced it (in a different location) and we have 60 GPM. Lots of water. The well has a depth of 255 feet.
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  #15  
Old 07-28-2005, 03:10 PM
N9IWP N9IWP is offline
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On "This Old House" recently (I think it was a rerun) the tested the current (shallow) well. At the start it got decent flow at a decent pressure, but after like 10 minutes, flow dropped to zero. They were pumping water out faster then the resevoir could regenerate.

(I don't know how wells are rated - is the 5GPM the rate that can be sustained indefinitely?)

Brian
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  #16  
Old 07-29-2005, 07:51 AM
dauerbach dauerbach is offline
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Yes, what they do is pump it out as fast as the pump can handle it. For only domestic use, the pumps don't necessarily even go above maybe 10 gpm because you could never use more. If you are putting in some type of geothermal heat pump they use bigger ones. Anyway, they try to pump until dry and then see what rate can be sustained for a couple of hours. If they never pump it dry then it becomes whatever the maximum pump rate they are using is.
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  #17  
Old 07-29-2005, 09:44 AM
CrazyFoo CrazyFoo is offline
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When they conducted the flow rate test in Jan, it showed 5 gpm, and they did it for 6 hours continuous until they stopped.
Do they put the pumped water into some tank, and then pump it back into the well after the test is complete?
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  #18  
Old 07-29-2005, 10:07 AM
dauerbach dauerbach is offline
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They would NEVER return water to the water table that has reached the surface. They just let it water the lawn or street, or whatever.
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  #19  
Old 07-29-2005, 10:24 AM
Debaser Debaser is offline
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I just built a two family house. Both units have three bedrooms and three baths.

My well only produced about a half gallon per minute when they drilled it. We tried adding more casing and digging down an extra 100 feet. (600 feet total). None of this really helped.

We then tried hydrofracking. This is when they shoot pressurized water down the well to force open a vein of groundwater. This got us up to 4 GPM.

In order to increase further from 4 GPM, we got a full 1 HP pump for the well instead of the standard 3/4 HP pump. This adds 1 GPM to your effective rate, I was told.

In addition to this we opted for a 62 gallon reseviour tank in the basement where the water comes in instead of the standard 32 gallon tank. If I had known about cisterns we would have asked about them.

Besides the 64 gallons in the house, we also have all the water in our 600 feet of well piping underground. This acts as a natural storage area for water.

So, having said all that: We've been just fine with 5 GPM. Of course, the unit next door to us is still vacant, so only time will tell. I water the lawn, run the dishwasher and do laundry, just not all at the same time. I will do any two of the three at once without worry, though. You can notice a slight drop in pressure at the tap or shower when several water consuming sources are running, but it's not that big of a deal.
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