Well water pressure loss over distance


B

bodega

Can anyone tell me of a simple way to determine pressure loss over
distance in Gallons-per Minute of well water? Example: Assuming I have
10 GPM at the well head, if I run a 2" ID water line 100', what loss in
GPM will I get? The tables I have been able to find all refer to loss
in water pressure (PSI). I need to go about 600' from the well head to
the new house and want to know if it is even practical to try to
utilize the old well.
 
C

Chas Hurst

bodega said:
Can anyone tell me of a simple way to determine pressure loss over
distance in Gallons-per Minute of well water? Example: Assuming I have
10 GPM at the well head, if I run a 2" ID water line 100', what loss in
GPM will I get? The tables I have been able to find all refer to loss
in water pressure (PSI). I need to go about 600' from the well head to
the new house and want to know if it is even practical to try to
utilize the old well.
According to Glover's Pocket Ref -2nd ed- 10 gpm thru a 2" plastic pipe will
loose .03 gpm per 100'.
Glover's Pocket Ref is a very handy book.
 
J

James

If you have anything near 10 gpm at the wellhead, you will have more water
than you will ever use, even if you went 3000 feet.

I have a very small spring that produces about one gallon per minute. I
pipe it 1200 feet uphill, and never have any problem.

Good luck !!


--james--
 
B

Bobk207

bodega said:
Can anyone tell me of a simple way to determine pressure loss over
distance in Gallons-per Minute of well water? Example: Assuming I have
10 GPM at the well head, if I run a 2" ID water line 100', what loss in
GPM will I get? The tables I have been able to find all refer to loss
in water pressure (PSI). I need to go about 600' from the well head to
the new house and want to know if it is even practical to try to
utilize the old well.
bodega -

I hope you don't lose any gpm....cuz all the water going to the pipe
at the well head better be coming out of the pipe at the
house....otherwise you've invented a "matter destroyer"

Your pump has certain preformance capability

flow (gpm) at various pressure (head) levels

ranging from.......

lots of flow at very little pressure to very low flow at high
pressure

the length, material & condition of the pipe & elevation change will
determinw how much head (pressure) drop will be suffered from well head
to house


here is a pressure loss calcaulator, you can play around with it

http://www.freecalc.com/fricdia.htm

2" PVC (600ft) with 10gpm flow will lose less than 1 psi
1.5" pipe ~ 3psi
1" pipe ~ 30psi

1.5" pipe is probably signifcantly cheaper than 2" & you can probably
handle ~2psi extra pressure loss

so unless you're pumping a long way uphill in addition to the 600 ft
AND you have a really wimpy pump you should be fine

cheers
Bob
 
J

James

On my spring which produces 1gpm, I have a two inch plastic pipe that
goes 1200 feet to our cabin, and has a total rise of 300 feet.


I have a 1 hp pump, that pumps water pefectly fine to the cabin, and I set
my pressure tank at 50 psi, and it works just great !

The spring site has a 300 gal storage reservoir, so our 4 member family
never runs out, even at this very very low water rate of 1 gpm.

If you have as much as 3 or 4 gpm, you can simply quit worrying about
running a pipe 600 feet. You can do all the calculations you want, but
what you really want to know is will you have plenty of water and good
pressure, and I can tell you that you will !!


--James--
 
M

Mike

James said:
On my spring which produces 1gpm, I have a two inch plastic pipe that
goes 1200 feet to our cabin, and has a total rise of 300 feet.


I have a 1 hp pump, that pumps water pefectly fine to the cabin, and I
set
my pressure tank at 50 psi, and it works just great !

The spring site has a 300 gal storage reservoir, so our 4 member family
never runs out, even at this very very low water rate of 1 gpm.

If you have as much as 3 or 4 gpm, you can simply quit worrying about
running a pipe 600 feet. You can do all the calculations you want, but
what you really want to know is will you have plenty of water and good
pressure, and I can tell you that you will !!
3-4gpm??? A water saving shower head uses 3 gpm.
 
B

Bobk207

Mike said:
3-4gpm??? A water saving shower head uses 3 gpm.

Mike-

Maybe he's talking about the well / spring flow capacity not usage
demand / supply at the house.

He's using the 300 gal storage reservoir at the spring site as a means
of supplying the drawn down demand of the cabin use?

A 1 hp pump would run dry in a heart beat if only supplied w/ 1
gpm.......

he needs ~140psi just to over come the rise.


Fed law water saving showerheads are 2.5gpm, faucets about the same

so the 3 to 4 gpm house supply would be rather lean

IMO a house / cabin with more than one person needs more like 10 gpm to
give decent performance.

cheers
Bob
 
B

bodega

Thanks for the info. I suppose a guy could always increase the pump
size if more pressure was need too.
 
B

Bob Morrison

In a previous post Bobk207 wrote...
IMO a house / cabin with more than one person needs more like 10 gpm to
give decent performance.
Bob's estimate sounds about right for the required flow rate available in
the house -- think showers and laundry + toilet flushing all at once.
That's why there should be a pressure/reserve tank at the house. As long
as the tank is big enough you can have a very low volume flow to the tank
from the well or spring.

BTW, this is the classic calculus problem of filling a tank at one rate
and drawing it down at a higher rate. How long before the tank is empty?

--
Bob Morrison, PE, SE
R L Morrison Engineering Co
Structural & Civil Engineering
Poulsbo WA
bob at rlmorrisonengr dot com
 
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Can anyone tell me of a simple way to determine pressure loss over
distance in Gallons-per Minute of well water? Example: Assuming I have
10 GPM at the well head, if I run a 2" ID water line 100', what loss in
GPM will I get? The tables I have been able to find all refer to loss
in water pressure (PSI). I need to go about 600' from the well head to
the new house and want to know if it is even practical to try to
utilize the old well.

I have read all of these and some key points are not covered. Yes 10 GPM is great head water from a Well, yes you can live on .75 GPM if that is all you get from a well. Yes you will have a pressure drop running a 2 inch line. For pressures drops look at http://www.freecalc.com/fricdia.htm as to the key points, you don't want to just get by, the lower you pressure the more the pump kicks on and off, the longer the pump runs the faster you kill the life of the pump. If your running your water line any distance and it does not provide you the pressure want then install a small storage tank and a little booster pump at the point of demand. Depending on how much you need you can use a 55 gallon drum and put a dress on it so it looks good. If your pump has a one inch discharge and you jump to a two inch line you going to reduce the pressure the pump needs to pump water. (That is good, this means the pump works less) You will then need to step it down as you get closer to the end so if you run a 2", run about 20 feet of 1.5, 20 feet of 1.25 then 20 feet of 1" and then again to a 3/4 line this will increase the pressure. You will create pressure but drop in GRM. you will get the most out of your pump in GPM if you run a larger line but you will decrease the pressure
 

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