New long water main help

[volscrazy65]

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?

 

[breplum]

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.

 

[MicEd69]

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.

 

[havasu]

(I appreciate both of your expert opinions!)

 

[volscrazy65]

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?

 

[MicEd69]

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.

 

[Valveman]

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.

 

[volscrazy65]

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.

 

[Twowaxhack]

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 ?