Diameter of 300' Waterline

[Bogan]

I have an accessory building 250 feet from the main house that I will be running a waterline, will be close to 300 feet total for tie-ins. The main house is on well water and has 2 full baths, kitchen sink, dishwasher, and clothes washing machine. I will be connecting to 3/4" CPVC in the main house to run the line to the accessory building. The accessory building has a full bath, kitchen sink, and clothes washing machine. The accessory building is close to four feet lower in elevation than the main house and both are single story. I am planning on using black or blue polyethylene pipe with 160 PSI minimum rating for the run. The accessory building is plumbed using Uponor AquaPEX. The waterline will connect to a 1" inlet, 3/4" outlet flow-through manifold for cold supply into 3/4" copper for the water heater to a 3/4" inlet manifold for hot supply. All service lines are 1/2" AquaPEX from the manifolds. Maybe not info is pertinent and ask if more info is needed for correct answer. Finally, the questions. In this situation the bigger the diameter the pipe the better? Originally considered 1 1/4', then 1 1/2", and now 2". Is 2" overkill? Can too big of a pipe have an adverse affect on water pressure in the main house? Once the new waterline is filled then a larger diameter only gives better pressure in the accessory building? For the piping material itself. Is there any difference between blue and black pipe besides color? Is stepping up to a 200 PSI rated pipe greatly beneficial? Thanks in advance for assistance and advice you may give.

 

[Terry]

https://terrylove.com/watersize.htm

The 1" is the minimum size you will want to go with for 300 feet on a one bath home. You can go larger and it doesn't hurt anything.