What is the minimum water supply line size for a bathroom renovation in a BC home?

The minimum water supply line size for a bathroom renovation in BC is 1/2 inch for individual fixture supply lines, with 3/4 inch required for the main supply line serving multiple fixtures. This follows the BC Plumbing Code (adopted from the National Plumbing Code of Canada) and ensures adequate water pressure and flow to all bathroom fixtures.

Individual Fixture Requirements:
Each bathroom fixture requires a dedicated 1/2 inch supply line for both hot and cold water. This includes toilets, sinks, bathtubs, and showers. The 1/2 inch sizing provides sufficient flow rate for proper fixture operation while maintaining adequate pressure throughout the system. Wall-hung toilets and pressure-assisted toilets may require 3/4 inch supply lines depending on the manufacturer's specifications — always check the fixture rough-in guide.

Main Supply Line Sizing:
The main supply line feeding the bathroom must be 3/4 inch if it serves multiple fixtures. In a typical bathroom with a toilet, sink, and shower, the main hot and cold supply lines running to the bathroom should be 3/4 inch, then reduce to 1/2 inch branches at each fixture. This prevents pressure drop when multiple fixtures operate simultaneously — critical for shower temperature stability when someone flushes a toilet or runs the sink.

Metro Vancouver Considerations:
Vancouver's municipal water pressure varies significantly by neighbourhood and elevation. Areas like the North Shore, Burnaby Mountain, and parts of Coquitlam at higher elevations may have lower water pressure, making proper supply line sizing even more critical. Older Vancouver homes (pre-1970) often have undersized 3/8 inch galvanized steel supply lines that restrict flow and should be upgraded to 1/2 inch copper or PEX during bathroom renovations.

Modern Plumbing Materials:
Most bathroom renovations in Metro Vancouver use either copper or PEX (cross-linked polyethylene) supply lines. PEX is increasingly popular due to its flexibility, freeze resistance, and lower installation cost. Both materials perform well in Vancouver's mild climate, but PEX offers advantages in earthquake-prone areas due to its flexibility. All supply line connections must include shut-off valves at each fixture for maintenance and emergency shutoff.

When Professional Installation is Required:
Any supply line modifications, including upsizing from 3/8 inch to 1/2 inch or running new supply lines to relocated fixtures, require a licensed plumber in BC. The plumber will ensure proper pipe sizing, adequate support and fastening (important in seismic zones), and compliance with BC Plumbing Code requirements for fixture spacing and valve locations. Permit requirements depend on the scope — replacing fixtures on existing supply lines typically doesn't require permits, but running new supply lines or modifying the main supply usually does.