How To Replace A Leaky Supply Line On Your Toilet

When it comes to saving water and money around your home, an odd, but important place to look is in your toilet. If left unchecked, a leaky toilet can add a substantial amount of money to your monthly water bill. Did you know that 10% of US homes have a leak that wastes on average 90 gallons of water per day? It’s true. Fortunately, identifying these leaks isn’t hard, you just need to know where and what to look at. One of the more common leaks you’ll encounter is a leaky water supply line, and fortunately, replacing it doesn’t require much in the way of special training or know how. Just follow these steps to swap out your leaky water supply line and start saving money and water today:

Things you’ll need for the job:

Towel
Wrench
New supply line (stainless steel)

How to replace a leaky water supply line on your toilet

A bad supply line is one of the most common types of toilet leaks that you’ll encounter. If there is water or wet spots or water stains underneath your supply line area, odds are, you might have a leak there. To make sure, you might want to clean and dry the whole area, and then come back in 15 minutes or so and check to see if visible signs of a leak have come back. You can also, at that point, run a dry piece of toilet paper over the area, much like checking under your sinks for leaks, and if the toilet paper is damp, you may very well have identified a leak.

Not sure where the supply line is? Check out the following image:

Typo is theirs, not ours! 🙂

Now, not all supply lines and valves will look like the one featured above, but they all work in the same way. To help you get a better understanding of how this process will work, be sure to check out the following video before beginning the removal of your old water supply line:

1. Turn off the water to the toilet and flush it. Turn the water supply valve to the right until it’s finger tight, then flush your toilet to drain out the water. If you don’t remember to flush the toilet, you could end up dumping a bunch of water all over your bathroom floor later on the in the process. Also, it may be a good idea to soak up all the water that has leaked out onto your floor if you haven’t already. Bathroom floors can be slippery when wet.

2. Loosen and remove the old supply line. Take your wrench and loosen the hex-nuts that connect the supply line to both the supply valve and toilet tank. Remember, it’s righty-tighty, lefty-loosey. Once the hex-nuts are loose the old supply line should easily lift free.

3. Put the new supply line into place. Take your new stainless steel supply line and attach one of the ends. It doesn’t matter which end you choose (supply valve or toilet tank), simply line it up and use your fingers to tighten the hex-nut into place. Now, attach the opposite end and use your fingers to tighten the hex-nut into place. The advantage of using a stainless steel supply line vs. a plastic one is in the supply lines flexibility. If you were installing a plastic line you’d have to cut it to size, however that means you’ll run the risk of cutting the line too short. By using a stainless steel line you’ll avoid that problem all together, and you can simply bend the supply line to fit. Now that the supply line is in place, take your wrench and snug up each of the hex-nuts. This will help to ensure that you have a water tight seal between the supply line and both the supply valve and toilet tank.

4. Turn on the water to the toilet. Now that your supply line is in place, all that’s left is to turn on the water and make sure that it’s working properly. Turn the supply valve to the left until you start to hear and see water filling the toilet tank. As the tank is filling, be sure to keep an eye on your supply line and look for any leaks. If you notice that you’re line is still leaking, it’s likely that you haven’t tightened the hex-nuts all the way. Simply take your wrench and tighten the hex-nuts into place.

If you’re looking for more ways to save water and money around your home, be sure to check out our green home improvement projects: Green Living Ideas, after all, is a top 20 home improvement website!

Photo courtesy of the Flickr Creative Commons (Toilet Sign,, flapper leak) Whiteley Home Inspections.

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Tags: diy, do it yourself, flapper leaks, how to, toilet leaks, water supply lines, wax rings

About the Author

Peter Young graduated from Pacific Lutheran University (PLU) with a degree in journalism and has made sustainability and eco-conscious living mainstays of both his professional and personal life. It was during his time at PLU that he began his journey with sustainability and it's what has led him to writing for Green Living Ideas. He currently resides in Honolulu and works for Pono Home, an energy efficiency company focused on reducing carbon emissions and promoting a healthier, greener lifestyle.