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.
Found another way around this?
Share your steps and trade-offs so fellow engineers don't have to reinvent the wheel. No account required.
- 1Run separate half-inch lines to each bathroom for hot and three-quarter-inch for coldDid this help you?
- 2Run lines all the way back to the main trunk linesDid this help you?
- 3Transition from copper to Pex for long runs using press fittings and Pex barbsDid this help you?
- 4hiring a professional plumberDid this help you?
- 5doing it little by little as a weekend project with permits and local inspectionDid this help you?
In their words
Unedited, grouped by where they were said, most upvoted first within each place, 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 ↗
“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 ↗
“I would appreciate advice on whether the proposed layout is workable and what changes would be needed to meet plumbing code.”source ↗
Where this came up
People with this problem also raised
- 2How to measure a toilet rough-in without removing it
- 7How to figure out correct plumbing and venting requirements for a remodel
- 2What size pipe do I need when combining two 3-inch pipes?
- 2Converting a bathtub to a shower with a 1 1/4 inch drain
- 6How to figure out a master bathroom layout with tight space
- 6How do I know which plumbing parts to buy for a DIY repair?