# help calculate water supply pipe size...1000ft run 100ft elvation



## 97catintenn

I've never done an install this far away from the street.  The house is 1000ft away from the road.  But being 1000ft away from the meter, with a 4 1/2 bath house, would a 1.25" pipe suffice?  I'm looking for the bare min here to meet 2009IRC


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## Builder Bob

100 feet elevation = .5 psi +/- per foot,  What is the needed flow for the house, friction loss is dependent upon water flow.... Not enough info provided.


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## north star

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97catintenn,

If you have 70 psi at the water meter at the street, and by the

time it travels the 1,000 ft. to the Residence it reduces down to

60 psi or less,  ...you may need to install a water pressure booster

pump on your potable water line.

A  1.25" sized line will [ typically ] provide enough volume for the

Residence.......If all 4.5 bathrooms and other plbg. fixtures, are

flowing at once, ...a booster pump would come on when the

demand is for more water is recognized........The pump would

then provide enough water volume, at the desired pressure,

throughout the Residence.

You will need to know what your current pressure is at the

street, or wherever the water meter is located.........You will

also need to know what the current pressure is at the Residence.

If there are 2nd stories or higher in the Residence, it will take

more effort to supply water to those higher levels, thereby

reducing the overall total pressure in the Residence as a whole.

See this article on booster pump sizing:

http://inspectapedia.com/water/Booster_Pumps.htm



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## Frank

Is irrigation planned?

Are there any high flow fixtures like multi head showers?

Using IRC 2012 P2903

Adding up bathrooms and assuming kitchen dishwasher, cloths washer and hose bib sfus and using conversion table

Gives  20 gpm

At 20 gpm the friction loss would be about 47 psi for 1.25 inch pipe.  NO GOOD unless have 120 psi plus at street

1.5 inch pipe gives 19 psi loss  No good unless have 90 psi plus at street

2 inch pipe gives 4 psi loss plus 43 psi for elevation loss if 100 ft above the street plus 20 psi min required at shower head plus 2 psi loss in distribution piping plus 5 psi for 2nd story---gives about 75 psi needed at street

Need 2 inch pipe from meter to house and if less than 75 psi at street may need booster pump as well.  If under 75 psi at street booster pump would need to be somewhat down the hill as most utilities require 20 psi min at pump suction with a 10 psi on suction side cutoff 606.5.5


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## Mech

Don't forget to include any losses through the water meter and back flow preventer.


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## 97catintenn

Sorry for the delay,

Water Dept said that there should be 100psi at the street.  So, if I'm reading the posts above right, then with my elevation of 100ft above the meter, then my loss is 43 psi.  That leaves me wtih 57psi before the 1000ft run and pressure loss to pipe size.

Thank you for your comments.  I would have thought 1.25" would have been plenty big enough for this install.


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## steveray

"Thank you for your comments. I would have thought 1.25" would have been plenty big enough for this install."

A wise man once told me....."Don't think!"


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