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?