How to Change a Toilet’s Water Supply Line

Changing your toilet’s water supply line is easier than ever. Gone are the rigid chrome tubes with compression fittings, unless you absolutely want to go that route. The simplest way is to use a braided stainless-steel flex tube. It doesn’t get much easier than this.

In offering these instructions, we’re assuming you’re only replacing the supply tube itself, and not the water supply valve. Toilet water supply lines carry water from a nearby cold-water supply line to your toilet tank to enable it to flush. Toilet water supply lines may develop leaks for a variety of reasons. The rigid tubes can bend or break if accidentally kicked or bumped.

Tools needed: bucket, bowl, towel, cup, crescent wrench, new flexible stainless-steel supply line.

Step 1: Measure the distance between your water supply valve (on the wall or floor beneath the toilet) and the point where the line connects to the toilet tank. Allow an extra inch or two for slack. Use your smartphone to take photos of your current water supply line in place, being careful to get both ends in the photo.

Step 2: Turn off the water to the toilet by turning the supply valve clockwise. If it’s a quarter turn ball valve, it will only require a slight turn to stop the flow of water. It it’s a gate valve, it will require several turns in the clockwise direction. If the valve is stuck, follow these instructions.

Step 3: Place a shallow bucket or bowl beneath each end of the water supply line to catch water that may come out when the line is removed.

Step 4: Remove the toilet tank lid and place it in a safe place where it cannot fall or break. Then flush the toilet until most of the water is gone from the toilet tank. Use a cup to remove as much remaining water from the tank as possible. You might even use a sponge to soak up residual water.

Step 5: Use a crescent wrench or open-ended wrench to unscrew the fitting from the supply valve, turning it counterclockwise. Then repeat the task where the line connects to the toilet tank.

Step 6: Take the existing toilet supply line with you to a hardware store or home center. Go to the plumbing section and choose a stainless-steel braided hose that is close in length. Note that it’s common for plumbers and homeowners to choose a longer line and install it with a gentle loop, so don’t worry if it’s longer than the original supply tube. Closely examine the ends to make sure they’re the same size as the ends on your old supply line.

Step 7: Connect the large end to the toilet tank’s fill valve nipple extending from the bottom of the tank. Hand tighten the plastic nut and do not overtighten it or you could break the porcelain tank. Next, connect the small end to the nipple on the angle stop valve. Hand tighten the nut, then use your wrench to tighten the connection just a bit more (never more than a quarter turn past hand tight).

Step 8: Turn on the water supply and check for leaks on either end of the line. If you notice a drip, carefully tighten the nut at that end to seal the connection, being careful not to overtighten. Then dry the tube, flush the toilet and check again for leaks.

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