How to Install a Toilet: Step-by-Step Guide

Before You Start

Installing a toilet is a straightforward project for most DIYers. Before you begin, measure the rough-in distance from the wall to the center of the floor flange. This measurement is critical because it determines which toilet will fit. For details on measuring and common sizes, see our article on rough-in sizes.

Choose a toilet that matches your rough-in and your preferences. Consider one-piece vs two-piece toilets and bowl shape. You can browse our best toilet guides for a wide range of options. If you are installing a new toilet in a home that has not had one before, you may also need to install a floor flange first.

If you are remodeling, you may also need to consider the height and clearance. The ADA provides guidelines for accessible design if you need a toilet that meets accessibility standards. See our guide on ADA requirements for more information.

Tools and Materials You Will Need

Gather the following tools before you start: an adjustable wrench, a screwdriver, a putty knife, a sponge, a bucket, a hacksaw (for stubborn bolts), and safety gloves. Having everything on hand will make the job easier and reduce the risk of interruption.

Materials include a new toilet (with its tank, bowl, and mounting hardware), a new wax ring, a supply line (if the old one is worn), and floor bolts and nuts. Some toilets come with bolts and a wax ring, but it is wise to verify that you have all the components before beginning.

Remove the Old Toilet

Start by shutting off the water supply valve, usually located on the wall behind the toilet. Flush the toilet to drain the tank and bowl as much as possible. Sponge out any remaining water from the tank and bowl to avoid spills when you lift the unit.

Disconnect the supply line from the tank. Remove the nuts and washers that secure the toilet to the floor. If the nuts are corroded, you may need to cut them off with a hacksaw. Rock the toilet gently to break the seal, then lift it straight up and set it aside.

Stuff a rag into the drain opening to prevent sewer gas from entering your home. If you are replacing the flange, now is the time to do that; see our brief on flange basics. Also inspect the floor area for damage or rot that might need repair.

Prepare the Flange and Set the Wax Ring

Inspect the floor flange to ensure it is in good condition. If it is damaged or corroded, you may need to replace it. A properly functioning flange is essential for a leak-free installation. See our guide on toilet flange basics for detailed instructions.

Scrape away the old wax ring residue from the flange and the floor. Use a putty knife and a rag to clean the area thoroughly. Any debris can prevent a proper seal and cause leaks.

Place the new wax ring onto the flange. Some wax rings come with a plastic funnel or rubber gasket; refer to our comparison of wax rings vs rubber gaskets to decide which type to use. Make sure the ring is centered on the flange.

Set the Bowl

Position the toilet bowl over the flange, aligning the mounting holes with the bolts. Gently lower the bowl onto the wax ring, using a slight twisting motion to compress the wax evenly. This helps ensure a continuous seal.

Do not slide the bowl after it contacts the wax; this can break the seal. Once seated, press down on the bowl to set the wax ring properly. The bowl should sit level; check with a spirit level and adjust shims if necessary. Shims are thin wedges that can be inserted under the base to level the bowl without tilting it excessively.

Secure the Bowl and Install the Tank

Install the nuts and washers on the floor bolts and tighten them alternately, a little at a time, until the bowl is snug. Avoid overtightening, which can crack the porcelain. The bowl should feel stable, but you should not have to force the bolts.

If you have a two-piece toilet, install the tank on the bowl next. Place the tank rubber gasket onto the bowl's inlet, then set the tank onto the bowl. Secure it with the tank bolts and nuts, tightening evenly. For a one-piece toilet, the tank is already attached, so you can skip this step. Learn more about one-piece vs two-piece toilets.

Connect the Water Supply and Test

Reconnect the supply line to the fill valve and the shut-off valve. Tighten the connections with a wrench, but avoid forcing them. A supply line that is too long or too short can cause strain on the fittings.

Turn the water supply back on and check for leaks at all connections. Flush the toilet a few times to ensure proper operation and to check the wax seal for leaks at the base. If you notice a persistent leak around the base, the wax ring may not have seated correctly. You might need to remove the toilet and start again.

Also check the tank for any overflow leaks. Some tanks have a fill valve that can be adjusted to control the water level. If your toilet has a dual-flush mechanism, test both buttons to ensure they operate smoothly. For more on flush types, see our article on dual flush.

Common Mistakes to Avoid

Many installation problems arise from a few common mistakes. One is failing to clean the flange thoroughly, which can cause a poor seal. Another is over-tightening the floor bolts, which can crack the bowl and lead to leaks.

Another mistake is not aligning the bowl correctly before setting it onto the wax ring. Once the bowl is down, moving it can break the seal. Take your time and double-check alignment. Use a mirror or a camera to see the bolt holes if necessary.

Finally, always use a new wax ring. Reusing an old ring will likely lead to leaks, and the extra effort is not worth the risk. If you have installed the toilet but notice a wobble, you may need to add shims under the base. Check for leaks after a few days of use to ensure everything remains tight.

What to pick for your installation

Questions

Do I need to replace the wax ring every time?

Yes, always install a new wax ring when reinstalling a toilet. The old ring will not reseal properly and can cause leaks.

What if the flange is broken?

If the flange is cracked or corroded, replace it before setting the toilet. See our flange basics article for guidance.

Should I use a wax ring or a rubber gasket?

Wax rings are traditional and reliable, while rubber gaskets can be easier to align. Our comparison covers the trade-offs.

How do I know if my toilet is leaking?

After installation, check for water around the base and at the supply connections. Slow leaks may appear as a damp spot or a persistent odor.

Can I install a toilet on my own?

Yes, with basic tools and careful work. If you encounter a corroded or damaged flange, consider consulting a plumber.

How long does a typical installation take?

Most installations take one to two hours, including removing the old toilet and making adjustments. Allow extra time if you need to replace the flange or address other issues.

Do I need to use plumber's putty on the base?

Plumber's putty is not necessary if you use a wax ring, because the wax provides a seal. Some installers add a bead of silicone caulk around the base for aesthetics and to prevent movement, but it is not a replacement for a wax ring.