Said It Here

Will half-inch pipes cause pressure drops in a second bathroom?

Using half-inch lines to supply two bathrooms can cause a noticeable change in shower flow and temperature when both are used simultaneously. This flow restriction prevents you from running both rooms at the same time without experiencing sudden pressure and temperature drops.

What people tried

Every workaround mentioned in the threads below. We haven’t tested any of them — and nobody here is claiming they worked.

  1. 1
    Run separate half-inch lines to each bathroom for hot and three-quarter-inch for cold
  2. 2
    Run lines all the way back to the main trunk lines
  3. 3
    Transition from copper to Pex for long runs using press fittings and Pex barbs

In their words

Unedited, most upvoted first, each linked to the thread it came from.

“If I add another bathroom with half inch copper will I have problems using both bathrooms at the same time or anything like that?”source ↗

kombuchy1 · r/Plumbing · 1 upvotes

“If you use 1/2 inch pipes for two bathrooms, the usage in one bathroom could make a noticeable change in shower flow and temperature in the other.”source ↗

Beet_slice · r/Plumbing · 1 upvotes

Where this came up

r/Plumbinghome renovationplumbing

People with this problem also raised