For shower supply lines, the standard shower pipe size is 1/2-inch in diameter for both the hot and cold water lines — this applies whether you’re running copper pipe, PEX, or another approved material. Some high-flow shower systems (rain heads, multiple shower heads, or systems with body sprays) need 3/4-inch supply pipe to deliver enough water pressure and volume, so always check your shower system’s manufacturer specs before roughing in the plumbing.
The shower drain pipe size is different from the supply size: standard shower drains use 2-inch drain pipe, which local plumbing code typically requires for adequate drainage. Don’t confuse the two — undersized supply pipe leads to weak water pressure, while an undersized drain pipe leads to slow-draining or backed-up showers.
If you’re not sure what size PEX, copper, or drain pipe your shower project needs, the team at 5 Star Plumbing can size it correctly for your specific shower system and code requirements.