Good vs Poor Wells - What makes a well a good well?

[oosik]

Its almost a national recognized standard - 5 gpm. And that's because its what FHA established over 50 years ago.

If your well will produce 20 gpm for an hour with 100 feet of drawdown - that's more than adequate for residential needs.

As we use to say - "that's more than enough water to create all sorts of sewage problems".

Look at it this way -

1) there is 145 gallons of water stored in 100 feet of 6" well casing
2) if you pump @ 20 gpm for an hour - that's 1200 gallons

Therefor - you pumped 1200 gallons in one hour and drew down the well 100 feet or 145 gallons. If there would have been absolutely no water being replaced into the casing - you would have drawn it down 845 feet. In other words, it would have been dry within 15 minuets. Since you only drew down 100 feet, it had to be replaced at 18 to 20 gallons per minuet. 18 gallons/minuet X 60 minuets = 1080 gallons. The 1200 gallons pumped in one hour came from the stored 145 gallons plus what was replaced at 18 to 20 gpm.

That's a good well - there is no other way to describe it. Now take a Valium and rest easy.

 

[Valveman]

The average house needs about 5 GPM minimum. If the well makes less than 5 GPM I would use a cistern. But even 1 GPM is 1440 gallons per day, and will run three houses if a cistern is used. I have drilled irrigation wells for people and they wouldn't pay me because the well was bad as it only made 500 GPM and they needed 1000. But I have drilled for other people who were tickled that the well made 1/4 of a GPM.

Pretty much anything in the water can be filtered out. As long as the water is wet it can be made usable.

 

[speedbump]

If it doesn't meet your needs, a cistern is the next step. You can easily make 1 gpm work. I wouldn't plan on a 5 acre plus garden though.
Your particular well is a very good well. People in mountainous areas would kill for volume like yours.

 

[TheMan419]

All I know about what makes a good well is the well at my house produces plenty of water. I can run a sprinkler in the yard or the dishwasher and still take a nice hot shower. If I flush the toilet and the wife is in the shower she does not notice.

At our old house flushing the toilet would mean the person in the shower was only getting a trickle of cold cold water.

Sounds like your well is producing quite a bit of water. If you are just using it for normal home use it is sufficient. If you want to water acres of crops maybe not.

 

[oosik]

An example - I inspected a small subdivision of 12 homes that put in a community water system from a well producing 25 gpm. The engineer simply had to size the storage tank accordingly. It worked exceeding well and everybody had more water than they could ever use.

 

[Valveman]

25 GPM is 36,000 gallons per day. With the right storage you could probably do 75 homes on that well.

 

[Egon]

All I know about what makes a good well is the well at my house produces plenty of water. I can run a sprinkler in the yard or the dishwasher and still take a nice hot shower. If I flush the toilet and the wife is in the shower she does not notice.

At our old house flushing the toilet would mean the person in the shower was only getting a trickle of cold cold water.

Sounds like your well is producing quite a bit of water. If you are just using it for normal home use it is sufficient. If you want to water acres of crops maybe not.

Pipe diameter can make a difference.

 

[turnkey4099]

All I know about what makes a good well is the well at my house produces plenty of water. I can run a sprinkler in the yard or the dishwasher and still take a nice hot shower. If I flush the toilet and the wife is in the shower she does not notice.

At our old house flushing the toilet would mean the person in the shower was only getting a trickle of cold cold water.



.

That was a problem with the house plumbing, not the well. I have a 20gpm well and big pressure tank. Still get way too hot shower if someone flushes the toilet. The toilet is plumbed in just upstream of the shower.

 

[Pettrix]

Its almost a national recognized standard - 5 gpm. And that's because its what FHA established over 50 years ago.

If your well will produce 20 gpm for an hour with 100 feet of drawdown - that's more than adequate for residential needs.

As we use to say - "that's more than enough water to create all sorts of sewage problems".

Look at it this way -

1) there is 145 gallons of water stored in 100 feet of 6" well casing
2) if you pump @ 20 gpm for an hour - that's 1200 gallons

Therefor - you pumped 1200 gallons in one hour and drew down the well 100 feet or 145 gallons. If there would have been absolutely no water being replaced into the casing - you would have drawn it down 845 feet. In other words, it would have been dry within 15 minuets. Since you only drew down 100 feet, it had to be replaced at 18 to 20 gallons per minuet. 18 gallons/minuet X 60 minuets = 1080 gallons. The 1200 gallons pumped in one hour came from the stored 145 gallons plus what was replaced at 18 to 20 gpm.

That's a good well - there is no other way to describe it. Now take a Valium and rest easy.

Well explained. Thank you. :thumbsup:

I was considering running the pump for an additional hour (2 hours total) at full volume to see where the water level would drop to. Might do that test at a later time.

Usually wells start to produce higher amounts after about 2-3 months of the initial drilling. My driller said this is because the fractures in the ground start to clean out and flow higher amounts of water.

 

[dfkrug]

Its almost a national recognized standard - 5 gpm. And that's because
its what FHA established over 50 years ago.

I have not heard of that near-standard.

Your post illustrates why a simple rating of x GPM to rate a well is not enough.

In California, the state decides and certifies a conforming well. The rule is that you must be
able to pump 3600 gal in a 24 hour period. That works out to a 2.5 GPM flow. That
rate ignores the storage requirements in rural areas (5000 gal min here). Sadly, that means
that a low-flow pump (e.g. solar) is non-compliant, even with huge storage.

Also, domestic well-drillers around here cite GPM flow rates for maybe 5 minutes, which is a near-
meaningless spec. They rarely measure the draw-down rate.