Step 5 · Locate and Mark Water Supply Lines
The water supply lines (or stub-outs) feed the hot and cold water to the faucet. Standard practice places these lines several inches above the drain line to prevent interference. A typical height is 21 to 22 inches from the finished floor. For horizontal placement, they are typically spread apart to allow room for the shut-off valves and supply hoses. A common configuration is to place the cold water line 4 inches to the right of the sink drain centerline, and the hot water line 4 inches to the left of the centerline (creating an 8-inch spread between them). Hot is always on the left, and cold is on the right. Mark these two locations on the wall. Again, review the vanity spec sheet to ensure these locations do not conflict with drawers, shelving, or the sink basin itself.