AboutDana Bostick Expertise Pretty much any residential plumbing questions. Note: I live and work in Southern California. We do not as a rule use boilers, hot water or steam heating systems or wells so my knowledge in those areas is limited. There are others here that can probably answer those questions better.
"We all is city folk" out here! What is a "well" LOL
Experience Licensed General Contractor with Plumbing, HVAC and Electrical sub-licenses
Question Would I lose pressure if I came off my 3/4" water line with 1" pipe? (using pvc) I don't want to replace the whole line because I am almost 1/2 a mile from my meter and the water company will NOT move the meter closer. (very rural area) Our pressure is okay right now but we are building a new house on the same land and want to come off the existing 3/4" line with 1" and cap it off to old house. Would this create a big problem?
Answer Hi Brandon,
You can't ignore physics. Given the very long run of your water main, I'll surprised you have any water at all at the existing house.
The water company is only responsible for the system up to your property line. It is unreasonable to expect them to run their pipes on your property. There are easement and access for maintenance issues at the least.
Flow rate measured in gallons per minute is determined by several factors.
1. Size of the pipe.
2. Length of the pipe run and any elbows etc. (friction loss)
3. The condition of the pipe. Clean, smooth interior or rough & corroded. (also friction loss problems)
Pressure has little bearing. You could develop several hundred PSI through a 1/4 inch line. You just would not have much flow rate in GPM.
Plumbing systems are designed based on flow rate/demand tables and calculated in "Fixture Units" which equate to about 7.5 GPM each.
3/4 inch, clean pipe is rated at 12 FU. 1 inch is rated at 24 FU. Now subtract for length, rise in inches above the meter, number of turns and condition of the pipe. The end result is what you have at the delivery end for your use.
Each fixture that needs water in the house is also rated for demand to allow for "functional flow". Toilet = 3, Tub/shower = 2, lav sink = 1 etc. One bathroom requires 6-7 FU, kitchen - 2, laundry - 2. So a typical 2 bath house requires about 16 FU. 3/4 inch pipe is the minimum size allowed these days. This, of course, ignores any irrigation requirements like sprinklers.
Tapping on a 1 inch pipe to the existing 3/4 may compensate for the additional length. Depending on how much farther you need to extend the line, it may work or you may find that it was just too much to ask of the 3/4. I suppose I would try it to see what happens. I suspect you will be disappointed in the results.
Obviously, the ideal solution would be to run a new 1-1/4 or 1-1/2 line from the meter to the new house location to allow for any expansion and irrigation demands.
Good Luck,
Dana
