New long water main help

Plumbing Forums

Help Support Plumbing Forums:

This site may earn a commission from merchant affiliate links, including eBay, Amazon, and others.

volscrazy65

New Member
Joined
Nov 19, 2024
Messages
4
Reaction score
0
Location
GA
I have to run a water main that's 1500' long with 250' in elevation gain with 180 psi at the meter. I was told by a septic tank guy wanting to run the water line that I'll need a 1" meter and 1" pipe with 3 pumps to have any pressure. I'm not wanting to deal with pumps at all. My local water co. said a 3/4" meter with 1" pipe and no pumps will be plenty. My options for meters are 3/4" $1800, 1" $3100 and 2" $5000. I'm planning on doing myself with HDPE. Also can I run two HDPE lines touching in the same trench or with they wear on each other?
 
the simple science is that you loose .433 lb of pressure for each foot of elevation change ...so that puts you at a static loss of 105 psi, leaving you 75 psi.
UPC chart only goes to 1,000 ft, and shows at over 60 pressure range, a 3/4" meter and 1" pipe gives you enough pressure for 11 fixture units and with 1-1/4" pipe, 21 f.u.
11 fixture units would break down to 1 10 f.u. tub/shower and one lav. no improvement with a 1" meter.
at 1,500', fugedaboutit without a pressure boost system.
Have an engineer design it unless you have a damn reliable plumbing contractor.
 
As breplum said, you will lose 0.433 psi per foot of elevation change. So, a more accurate loss for 250 feet of elevation is 108 psi, leaving you with 72 psi, which is great. However, the pressure drop through a straight plastic 3/4" line 1,500' long at a mere 5 gpm of flow is almost 35 psi. So, that leaves you with a dynamic pressure of around 37 psi. That is workable, but you will experience noticeable pressure changes when multiple fixtures are being used. Using a 1" line, the corresponding pressure drop is only a little over 10 psi, leaving you with a dynamic pressure of around 62 psi. This engineer says you need to use a 1" line. And the water meter size doesn't matter much with 180 psi feeding it.
 
Thanks so much guys. If we weren't happy with the pressure at the top, could we install a pump at the top or would it need to be at some other point or points down the line? Would some kind of tank be useful at the top/house?
 
Yes, you could install a booster pump, and it wouldn't matter where you put it, so putting it at the house would be best. But why would you? Adding a mechanical device at a cost with ongoing maintenance and operating cost to save the price between 3/4" and 1" line isn't a good tradeoff, IMHO. And no to the tank at the house.
 
From someone who could help you with the pump, all good advice above. Don't use a pump when it isn't needed. Just put in large enough pipe and take advantage of the 180 PSI at the meter. Should leave you plenty at the house.

A little experience with long poly water lines I would advise to snake it along and not use compression couplings. Poly will contract or expand about an inch per 100' with every 10F change in temperature. A 1500' line could change length by a couple feet as the season changes. Snaking along give it a place to go instead of crawling up out of the ditch. Lol! I also went back and used butt fusion welds where I had tree root problems at the connections. Tree roots will grow right through the o-ring on a compression coupling or follow a thread in a threaded connection to the inside of the pipe to get water.

If at any time the meter pressure decreases and you need a pump, adding one is easy. Installed where you still have a little incoming pressure it can boost pressure up to whatever is needed.

Multistage Booster and PK1A.jpg
 
Yes, you could install a booster pump, and it wouldn't matter where you put it, so putting it at the house would be best. But why would you? Adding a mechanical device at a cost with ongoing maintenance and operating cost to save the price between 3/4" and 1" line isn't a good tradeoff, IMHO. And no to the tank at the house.
I with you. I'd much rather spend extra and not have to deal with a pump. I would even put in 1 1/2" or 2" if that would help.
 
I have to run a water main that's 1500' long with 250' in elevation gain with 180 psi at the meter. I was told by a septic tank guy wanting to run the water line that I'll need a 1" meter and 1" pipe with 3 pumps to have any pressure. I'm not wanting to deal with pumps at all. My local water co. said a 3/4" meter with 1" pipe and no pumps will be plenty. My options for meters are 3/4" $1800, 1" $3100 and 2" $5000. I'm planning on doing myself with HDPE. Also can I run two HDPE lines touching in the same trench or with they wear on each other?
What is your water demand in GPM ?
 
Back
Top