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.
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 !!
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
lots of flow at very little pressure to very low flow at high
the length, material & condition of the pipe & elevation change will
determinw how much head (pressure) drop will be suffered from well head
here is a pressure loss calcaulator, you can play around with it
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
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 !!
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
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.
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
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