How much is considered minimum of GPM for a well?

LesBaer45

LesBaer45

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Looking at a parcel that claims to have a current 5 GPM well which strikes me as "not much" but then again I honestly don't know what would be considered "ok" for a 3/2 home. Grew up on wells but I never knew the production rate.

Supposedly already has a valid septic permit / plan so at least that's done.
 
@Armed4defense will have good advice

When we built our house and had the well drilled, the flow was only 2.2 gallons per minute, which the well driller told us was marginal. So they drilled the well an additional 200 feet deep to create a reservoir of water. like the well has a buffer to draw from and then it can recover if the house is drawing faster than the well inflow.
They told us an estimated 1 gallon of storage is created per foot of well depth below the water table, so that got us at least 200 gallons buffer.
We have had no issues with that flow rate and buffer in our house, family of 4. Lived here for 15 years.
 
Depends. How deep is it, ie how much water volume? Around here wells are typically 1 to 1.5 gpm, which is the recovery rate, but the wells are about 500’ deep and the static water line is about 30’ which translates to a lot of water. Consequently, even though the recovery rate is low, it’s not a problem.
 
Does well have a tag you can read. If recent the company that dug the well should have records. Is it it a bored , drilled, or hand dug.
Mortgage lenders if I remember correctly like to see 5gpm minimum.
House I lived in when I was born was a 1ea. 1 gallon bucket a minute. Helped pop put in a well pump. we got about 2 gallons a minute. Short showers were required
 
According to the local water utility, the average person used about 900 gallons per month. Using my example of a 520’ well with 30’ static and assuming an 8” bore that’s about 1,300 gallons or more per than a person’s usage for a month. Consequently, it’s plenty of water even with a slow recovery.
 
Most residential wells from the triangle west are 6" wells.
An 8" well is almost twice the cost per foot of a 6" well
 
Our previous well was about 4 to 5 gallons per minute, and our well ran dry. We had it drilled several hundred feet deeper and now we are at 25 gpm. Prior to getting our well redrilled we would routinely run out of water.
 
Chuckman said:
Our previous well was about 4 to 5 gallons per minute, and our well ran dry. We had it drilled several hundred feet deeper and now we are at 25 gpm. Prior to getting our well redrilled we would routinely run out of water.
Click to expand...
Did Hudson well deepen the well for you?
 
5 is good to go in my opinion, I use alot of water washing a house, I always check the gis data for the well permit before quoting a job. More than 4 gpm and a couple hundred feet of reserve and I'm usually pretty comfortable. Less than that I add $ for hauling water. I've had a few wells with good gpm have the water turn brown within 20 minutes of running, so gpm is not always the only indication. I have 15 gpm and routinely fill up a 525 gallon tank without issue. When they were drilling my well, at 300' they only had 2gpm, well driller said it would be fine for a standard home. I asked him to go a little more and he hit 15gpm at 340', then went another 50'.
 
Driller was sceptical about 1.5gpm at a house I built (and I agreed); so we decided to go deeper looking for higher rate. Ended up @ 600' with the same 1.5gpm, but (as mentioned above) 6" diameter gave us 1.5gpf, and water table was at 100', so 500 x 1.5 = 750g reservoir. Lived there 9 years & never lacked for water.

Another way to put it is the refresh rate isn't the only factor in the equation.
 
1 gpm is legal minimum in NC, although I have seen less. Wells are funny things - soil type is critical. Sometimes a work around is to put in a larger pump tank or several smaller ones in series to give well longer recovery time. With what you have and a proper pump tank size you should be good. Well recovery time is often even more important than gpm although both play a role in getting the water you need. Another factor that may have been mentioned is static water level, too low and you will not be able to run a higher pressure switch as pump will not be able to build up sufficient pressure to cut off, unless you lower pump output. Lower output on pump means you can put pump lower in the well. Many variables and solutions are possible. Hope any of this helps, I have found each case is different -not one size fits all. PM if you have other concerns - I'll try and help.
 
Here is where soil type does matter regarding water supply wells in NC.
The rest of NC, the wells are in the geologic formation 17143327406141816424062869965627.jpg
 
Ok, so sounds like it may be nothing to get overly concerned with right off the bat.
I have to go visit the actual site, I'll locate the well head and see what info is on it that might be pertinent based on the comments here.
It's up in the mountains and may already be a deep well in rock or something expensive. I figured at worst I could put in a cistern type of a deal for a reserve and just let if fill up as needed.

Of course it maybe a crappy location and we have no further interest in it as well. Just doing some preliminary fact finding. No rush.

Thanks ya'll. I now have to go brush up on my hydrology.
 
I built my house 37 years ago. We drilled our well, it went 310 feet deep and 98 gpm. She hit like a Texas oil gusher! Never had an issue and I supply 2 homes and the pool house. I can throw 2 hoses in the pool, 28000 gallons and fill it completely in 24 hours. I never dreamed I’d hit a vein of water so good. My brother drilled his almost 500 feet and got 4 gpm. The school behind me is on an artisan well and I must have hit the same one.
 
Not to hijack this thread or to get into a pissing contest but - the minimum I stated came from a state well inspector when NC had a well certification program years ago. Things may be different now -I don't know. To say output and recovery are the same thing, well I am not sure if we are communicating, but say you have 2 wells, both have an output of 10 gpm, depending on location and numerous factors, they can recover( time it takes for well to return to static water level) at greatly different rates -not the same. As with soil type affecting a well, depending on type of soil, it can make a huge difference on water output and quality whether well is drilled in rock, clay, sand etc. I don't know @WellCC or @WaterDrillNC, or your experience but don't send me some poorly scanned pages of regs and expect me to be impressed. I'm out of the business, have old eyes and don't care. @DangerRuss mentioned I might have some thoughts, which I gave, from 35 years of doing this work, my observations come from practical experience, not from a book of regulations. Always happy to help if I can. Y'all have a good day.
 
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In NC residential wells from the piedmont west are primarily 6" open end rock wells which rely on fractures to provide water. Casing minimum is 20' (43' in a few specific areas with geology issues) and 20' of grout. Per 2C .0107, well casing is to be set at least 5' into competent rock to seal off upper strata (soil, saprolite).
NC has a permitting and inspection program for domestic water supply wells since July 1, 2008 via local health departments.
 
It’s not about gpm.. it’s about recovery..
if there is 20 gallons in the well it will take 10 minutes to empty it at 2 gpm.
If the water is replaced at 2 gallons per minute in 10 minutes it will replace the water and you’ll never run out of water.
If the water is replaced at 1 gallon per minute the draw will exceed the recovery rate and someone will run out of water.
 
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