How to install a new Kohler or Toto toilet when it leaks: hard to DIY?

Installing a new toilet is a DIY project that can give your bathroom a facelift. But, it’s not as simple as it looks. Installing a new toilet requires a water supply, which means you’ll need to open the wall. You also need to install drains so that wastewater from the toilet can travel outside your home. Read on for instructions on how to install a new toilet. We are going to discuss each step to help you get started. 


Tools needed to replace a Toto or Kohler toilet

Before you begin, make sure you have all the tools you need. You’ll need 

-an adjustable wrench to tighten the nuts 

-a big bucket to catch water, a sponge to clean the area

-an old rag to catch water

-gloves to protect your hands.

-a tape measure, a pencil, a saw, 

-a drill, a leveling tool

-the flexible water supply line

-an angle shut off valve

-the toilet flange and wax ring

-anchors to hold the toilet flange down

-the toilet itself

Turn off the water supply and drain the pipes

Turn off the water main supply to your home. Once this is done, we can drain the pipes near your toilet by opening the nearby faucets. Once there is no water coming out of them anymore, we can cut open the pipe. 

If we still have to run the pipe, we can connect the PEX pipe to the manifold and unroll the pipe. You might have to drill a hole in the wall so that the pipe can run through it. Make sure to use enough anchors for the pipe. If there is no space on the manifold, you might have to expand it. 

If you have a copper pipe, it is possible to connect a PEX pipe to it or you can add another piece of copper (we have outlined how you can do this without soldering HERE). Just make sure that you have enough water pressure by picking a pipe that is wide enough. Toilets don’t need that much water so generally, it shouldn’t be too much of a problem. 

The pipe should come out of the wall so that it is easy to attach the angle shut-off valve.

Install the angle shut off valve

The angle shut off valve allows us to close the water supply line if there is a toilet leak. This is installed against the wall. There are kits that contain all the parts that we need, from the brass ring to the angle stop valve itself. You can install this with two wrenches as you just need to add the ring and tighten the nuts. One wrench holds the valve whereas the other one tightens the nuts. Once this is done, we can start working on the drains.

If you have a copper pipe, you should clean and deburr it. A PEX pipe should be calibrated so that it is round before you connect it to the valve.

Install the toilet drain and flange in the bathroom

If you have a standing toilet, the PVC drain would go through the floor. We generally pick a 4-inch drain for this. If you have a hanging toilet, it should go through the wall. We have to take the size of the drain into consideration. For commercial buildings, it is necessary to calculate how wide the drain should be. For houses, plumbers often pick the standard size. We have to run this drain at an angle of roughly 6 degrees. This makes sure that the wastewater flushes away.

The back side of a hanging toilet. Image by PlumbingInstantFix. All rights reserved.

 The goal is to connect this to the other main drain. Make sure that you connect it to the right drain as grey (water from the sink and shower) and black water (toilet water) should be separated in a lot of instances. You can connect it at a 90-degree angle (if both the main drain and the toilet drain have a different diameter) or 45-degree angle (if both drains have the same size).

Check your local code for the exact requirements as these might differ from what we have listed here. Getting this right is essential to avoid clogs later on. It is the most challenging part of this project. In most instances, it is best to let a plumber do this so that there are no problems with this down the road. 

Once we have the drain installed, we can cut it flush with the floor so that we can isntall the flange. The flange connects the drain with the toilet. It is a plastic ring that we will keep in place with anchors and PVC glue. We have discussed how you can use PVC glue HERE. We can predrill the holes to install these anchors. The toilet flange should have two bolts sticking out of it.

Add the rubber or wax ring to the toilet flange

The wax ring ensures a tight connection between the toilet flange and the toilet itself. This ring might need to be replaced after a decade as it deteriorates. Place the wax ring on the toilet flange, and make sure that it is in the middle of the anchors. A rubber ring can be installed as an alternative.

Connect the toilet tank to the toilet bowl

 Now we can prepare the toilet. For a standing toilet, we just have to connect the toilet tank and toilet bowl with each other with bolts. There are special wrenches that make it easier to tighten them. Don’t overtighten them though as toilets are quite fragile.

We add the toilet seat in the same way. Just tighten the bolts properly. Installing the hardware in the toilet tank is quite straightforward as there are kits that help you do this.

Installing a hanging toilet is different as you start with adding the water tank frame to the wall. It is only later on that you add the toilet bowl. There are instructions in the box that explain how you can add the hardware to the toilet tank. You can use the adjustable feet to change the height of the toilet.

The same is true about the anchors that allow you to change the distance from the wall. We can then attach the toilet tank to the wall. We can add the wooden frame and cover after this. Then we can add the tiles to this frame. Then the toilet tank is added. Each manufacturer has a different system so check the instructions that are provided with your toilet.

The next step is to add the toilet tank to this. The frame should provide the anchors so we just have to use these as a reference point and attach the toilet there. 

Attaching the toilet to the toilet flange

 The toilet flange had two bolts sticking out. We are going to use these as reference points and place these in the holes in the toilet base. Once this is done, we are going to push the toilet down so that the wax ring can connect to it. To finalize things, we are going to tighten the bolts. If needed, we can cut them down with a saw and add the plastic covers over them. 

Check that the toilet is standing level before you move forward.

Connect the water supply line

We already have the angle shut-off valve. Now we can add the flexible toilet pipe. This is done by tightening bolts. You can use a wrench to do this. Just connect it to the valve and the toilet. You can also add a copper connection if you prefer this.

Once you are sure that the connection is done properly, you can open up the water supply. The toilet tank should fill. Make sure that there are no leaks at this point! We should be able to test the toilet now. 

Clean up and wrap up

Once you’ve finished installing your new toilet, clean up and wrap up the project. To clean up, use a rag to wipe up any water on the floor, and then mop the floor with a wet mopping pad to clean up any wax residue. Test the toilet and make sure that there are no leaks. 

Toilets only last about 15 years so it can be a good idea to replace it once your toilet reaches this age as a lot of parts starts to wear out.