How to Properly Set a Toilet to Prevent Leaks

White ceramic toilet with lid open and pipes underneath

The Spruce

Overview
  • Working Time: 30 mins
  • Total Time: 4 hrs
  • Skill Level: Beginner
  • Estimated Cost: $15 to $25

When you are replacing a toilet or resetting an existing toilet after a repair, there are a few key things to check to ensure a good seal and prevent leaks. You want to make sure the toilet sits level and does not rock on the floor, as this can compromise the seal. Toilets are sealed to the floor flange with a wax ring, but the height of the flange and the tightness of the flange bolts that secure the toilet to the floor can affect the ring's ability to create a watertight seal.

What Is a Toilet Flange?

A toilet flange (also known as a closet flange from the term "water closet") is simply the ring that sits on the floor beneath your toilet and extends into the drain pipe. It is usually made from PVC, but can also be metal or rubber.

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Watch Now: How to Properly Set a Toilet to Prevent Leaks

What You'll Need

Equipment / Tools

  • Pliers or adjustable wrench
  • Utility knife

Materials

  • Flange extender (optional)
  • Toilet wax ring or foam gasket
  • Plastic toilet shims
  • Silicone caulk

Instructions

Materials and tools to prevent toilet leaks

The Spruce

  1. Check the Flange Height

    When preparing to install the toilet, the first thing to confirm is the proper flange height. With the toilet removed, you can see the toilet flange and measure its height above the floor. The optimum flange height to aim for is 1/4 inch above the finished floor. This typically allows for almost any type of wax ring to be used and still ensure a good seal. If you recently tiled or changed the bathroom flooring, the flange height is likely less than optimal.

    To get the necessary clearance from the floor, you can add a toilet flange extender, which is quick and easy to install. Flange extenders are commonly sold in 1/4-inch and 1/2-inch sizes to raise the height of the existing flange to either of those measurements. Most extenders come with long bolts, which may be necessary if the flange is below the floor level.

    Exposed toilet flange to adjust height

    The Spruce

  2. Secure the Closet Bolts

    The two closet bolts that anchor the toilet base to the flange must be properly secured to the flange. These are the long bolts that stick straight up out of the flange.

    It is a good idea to use a nut and washer to hold the closet bolts to the flange from the top side. This will ensure you do not knock the bolts over when installing the toilet, and it will make it much easier to remove the bolts in the future. When you are buying a toilet or replacement wax ring, check to make sure that it comes with extra nuts and washers, or buy an extra pack while you are at the store (they are sold in inexpensive sets).

    Tip

    If you are using a toilet flange extender, you must bolt the extender to the original flange.

    Closet bolts secured on toilet flange

    The Spruce

  3. Place the Wax Ring and Toilet

    Choose a wax ring of the appropriate size. The type with a polyethylene plastic sleeve provides a great seal and fits most standard drains. If the toilet's floor flange height is slightly less than 1/4 inch above the flooring, you can use an extra-thick wax ring to make up the difference. Do not be tempted to stack up two wax rings because this setup tends to leak. Installing a flange extender or using an extra-thick wax ring will work much better in the long run.

    Place the wax ring on the closet flange, not on the toilet. Pick up the toilet and set it evenly over the closet flange, making sure the bolts come through the bolt holes in the toilet base. Fine-tune the toilet position, so it's right where you want it, then push it straight down so it smashes the wax evenly. Push until the base of the toilet rests on the floor.

    Tip

    So-called "waxless" toilet rings, such as the Sani Seal, are foam gaskets that replace conventional wax rings. These are great options for DIYers because you can reuse them if you need to remove or reposition the toilet. With wax rings, once the ring is compressed by the toilet it cannot be used again.

    Green wax ring held over closet flange

    The Spruce

  4. Level the Toilet

    Before you bolt the toilet down, confirm that the base is stable and level by carefully rocking it from side to side and back to front. If it does not sit perfectly flat, it will rock and is more likely to leak over time. To correct this problem, slip toilet shims between the base and the floor to stop the rocking before bolting it down.

    The location and the number of shims needed depends on the toilet and the floor; every situation is different. Getting the toilet shimmed before bolting it down will help ensure it does not come loose in the future. Once the toilet stops rocking, you can bolt it down with a nut and washer on each closet bolt.

    Warning

    Be very careful when tightening the washers and nuts against the toilet base; they should be snug but not overly tight, which can crack the toilet.

    Toilet leveled under toilet base

    The Spruce

  5. Caulk the Base

    Cut off any portion of the toilet shims that stick out using a utility knife, and caulk around the base of the toilet with silicone caulk. This will give a little more protection against movement in the future, and it will make the base area easier to clean because you will not get a layer of dust and detritus under the toilet where you can not reach it.

    As an option, it's a good idea to leave the back end of the base (out of view) without caulk so that, if the toilet leaks at the floor, the water can flow out and alert you to the leak before it causes damage to the subfloor.

    Caulking a toilet
    Aaron Stickley
Article Sources
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  1. Plumbing: Toilets -Loose Toilet Issues. HomeSight Inspections.