what size supply line for bathroom sink
Find the correct sink piping to fit the water supply line, which is usually a 3/4-inch copper pipe. Measure the end of the main water supply where the piping attaches near the valve shut-off to determine the pipe size.To fit the sink piping to this line may require a 1/2 reducer, as the lines running from the supply line to the sink are usually 1/2 inch lines.nstructions. Measure the distance between the main water valves underneath your sink to the sink faucet. Main lines typically run through floor joists and branch up into the walls in the bathroom and kitchen. The lines stub out underneath the sink with the left supply being hot and the right supply being cold.