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Pipe size to water pressure

Richard Trehewey holds a toilet

I'm in the planning stages to build a country home that sits 700 feet back from the road and county water main. What diameter pipe should be used to cover this distance? The county line that will be tapped is a 3-inch line and we hope to get the maximum allowable water pressure. It doesn't seem realistic to lay three-inch pipe the entire way. At what point should we go to a smaller diameter pipe?


A typical single family house with two bathrooms, a laundry, dishwasher and kitchen and one outside faucet has a capacity of 28 factor values. (Factor values measure how much water a particular fixture needs.) Residential installations must have a demand factor (which measures how much a fixture is used) applied to this number to get the net factor value. The residential multiplier is .50 so this typical house would have a net factor value of 14. One inch pipe is good for 9.1 to 16.5 factor values. If you are 700 feet back, I would upsize at least one size to 1 1 " pipe. If your house is bigger and you are in doubt of its size, there is no pipe that would be "too big." Less friction from larger pipes means more potential water pressure.


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