How to Repair a Leaking Toilet Supply Line

Water on the bathroom floor is a signal that your toilet supply line has reached the end of its functional life. Whether the leak is a slow weep at the coupling or a sudden drip from the hose itself, this is a repair that demands immediate attention to prevent floor damage and mold growth beneath your vanity or baseboards. A successful repair requires a steady hand and a methodical approach to sealing connections. When done correctly, your new supply line will provide a secure, leak-free connection that lasts for years, giving you peace of mind that your bathroom floor stays dry and your home remains protected from water damage.

1. Kill the Water First. Locate the shut-off valve behind the toilet and turn it clockwise until it stops. Flush the toilet to drain the tank, then hold the handle down to remove any remaining water.
2. Detach Both Ends. Use an adjustable wrench to loosen the nut at the toilet fill valve connection. Repeat this for the nut at the shut-off valve, turning counter-clockwise to detach the hose.
3. Clean the Valve Seat. Examine the valve threads for mineral buildup or corrosion. Use a stiff nylon brush to clean the threads so the new hose seats properly.
4. Prep the New Line. Ensure your new braided stainless steel line matches the length and diameter of the old one. Confirm that the rubber gaskets inside the couplings are seated and intact.
5. Install and Secure. Thread the new supply line onto the shut-off valve and the toilet fill valve by hand. Tighten each end until it is snug, then give it a final quarter-turn with your wrench.
6. Verify No Leaks. Slowly turn the shut-off valve counter-clockwise to restore water pressure. Watch both connection points closely for any sign of moisture.