What size tap do I need? 3,500 feet from tap to building?

[ryan817]

Wanted to asked if anyone could recommend a tap size / line size to service a building located approximately 3,500 feet from the existing waterline. Building contains one lav, one toilet, kitchen sink, waterline for ice maker and two hose bibs. Any assistance would be appreciated. Thanks.

 

[Jadnashua]

At 15gpm, maybe high for your maximum use, but hose bibs could easily take all that, a 2" pipe would have a pressure loss of about 7psi. It goes up quite a bit if you drop to 1.5" (31.1psi loss) at that same rate, and a 1" pipe would have friction losses over 200psi! A 3" pipe would only have a friction loss of slightly over 1psi at that flow rate. http://irrigation.wsu.edu/Content/Calculators/General/Pipeline-Pressure-Loss.php . If you then add in some fittings, the friction losses go up.

Note that when you aren't using any water, unless there are elevation changes, your pressure would be the same as at the tap. It only drops when there's flow, and goes up quite a lot as the flow rate goes up. Then, you have to consider maximum fps in the pipe to ensure you won't have erosion problems. A figure of 5pfs is usually considered a safe continuous rate, but higher short-term rates usually aren't a big issue, it does increase friction, though which results in pressure drop.

 

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[hj]

Tap size and pipe size are two completely different issues. A 3/4" tap would give all the water you need, but for that distance you would probably want at least a 1 1/2" pipe.