How to Install a Toilet: A Guide to Bathroom Transformation

Installing a toilet might seem intimidating, but with the right tools, preparation, and a little patience, it’s a manageable DIY project for any homeowner. Whether you’re in Austin, TX, replacing an outdated fixture, Seattle, WA, upgrading to a more water-efficient model, or Chicago, IL, tackling a full bathroom renovation, knowing how to install a toilet can save you time, money, and the hassle of hiring a pro. With a few key steps, you can confidently refresh your bathroom and improve your home’s function and comfort.

Parts of a toilet

Understanding the basic parts of a toilet makes installation easier. A toilet has two main sections: the tank, which holds water and contains the fill valve, flush valve, and flapper; and the bowl, which connects to the drain. Key components also include the wax ring for sealing and bolts to secure the toilet to the floor. Knowing these parts helps streamline the process.

Types of toilets

There are primarily two types of toilets: two-piece and one-piece. Two-piece toilets are the most common, featuring a separate tank and bowl. They are typically more affordable and easier to transport. 

One-piece toilets have the tank and bowl fused together, creating a sleek, modern look and simplifying cleaning. Wall-hung toilets are another option, mounting to the wall and freeing up floor space. Selecting the type that fits your needs and bathroom style is important.

Preparing for the installation of a toilet

Before you begin, preparation is essential. Measure the rough-in distance — the space between the wall and the center of the drainpipe. This measurement determines the size of the toilet you need. Turn off the water supply to the existing toilet and flush it to empty the tank. Gather all necessary tools and materials and clear the workspace. Ensure adequate lighting and ventilation. 

As Desiree Rivera of Master & Sons Plumbing puts it, “Installing a toilet without proper measurements is a fast track to realizing it’s wedged in all the wrong ways. Forgetting to shut off the water turns your bathroom into an unexpected indoor swimming pool. Wax rings stick to everything except where they’re supposed to—your hands, your clothes, and maybe even your pet.” A well-prepared space minimizes potential issues and streamlines the process.

To install a toilet smoothly, it’s important to gather everything you need before starting. “Gather all your tools like a small adjustable plier, putty knife, rags or towels, a bucket, a level, a shop vac and a caulk gun.” Joel B. Bliss of Bliss Plumbing recommends. “Then make sure you have all your supplies such as the new toilet, wax ring, new supply line, closet bolts and caulk.”  

Having all these items ready prevents interruptions and ensures a smooth installation. Investing in quality tools will make the job easier and more efficient.

Safety considerations

Safety should always come first when undertaking any home project. Wear gloves and eye protection to avoid injury and exposure to unsanitary conditions. Be mindful of the weight of the toilet during removal and installation to prevent back strain. When handling tools, maintain a firm grip and ensure proper usage. If encountering any unexpected issues, shut off the water supply immediately. Safety precautions prevent accidents and make for a seamless experience.

Removing the old toilet

Once safety precautions are in place, the next step is removing the old toilet — a process Joel B. Bliss of Bliss Plumbing walks through in detail below.

“First, make sure the water to the toilet is turned off. This may sound simple, but believe it or not, this step is often overlooked. Once you turn the water off and have flushed the toilet, use the shop vac to suck out all the remaining water from the bowl and the tank. You will appreciate this when you go to move the toilet and don’t have all that water sloshing around. 

Then disconnect the water supply line and remove the nuts from the closet bolts at the base of the toilet. You may need to use the putty knife to pop off the decorative bolt cover to gain access to the nuts. After removing them, you are free to pull the toilet. Check the area for any damage under the toilet and make sure that the flange is not cracked or showing signs of stress after you scrape off the old wax ring.”

Gently rock the toilet to break the wax seal and lift it off the flange. Be prepared for residual water. Plug the drain opening with a rag to prevent sewer gases from escaping. Carefully clean the area to prepare for the new installation.

Preparing the bathroom floor

Scrape away any old wax residue from the flange and floor, and thoroughly clean the area to remove any remaining caulk, dirt, or debris. “In preparation for installing a new toilet, please remember to get as much caulk, dirt, debris off the floor once the old toilet is removed,” advises Angela from Osborne Plumbing and Drain. 

Inspect the flange carefully for any damage or corrosion—replace it if necessary. Also, check the subfloor for signs of rot or softness, particularly around the flange. “Even a slight softness can lead to instability or leaks over time,” warns Dar Kashi of Kashi Custom Homes. 

Make sure the floor is level and dry before continuing. While a new wax ring is the traditional choice for sealing the toilet, some pros prefer rubber seals for easier alignment, especially in remodels where flange height may vary. A properly prepared floor ensures a watertight seal and a stable base for the new toilet.

Installing the new toilet bowl

Inspect and prep the floor

Start by making sure the subfloor is dry, stable, and free from moisture or mold. This step is critical to preventing future leaks or rocking. “Be sure the floor is free of any moisture and mold. You always need to be sure the floor is stable and secure,” say Nino and Christina, owners of Plumbers R Us.

Check and install the flange

Ensure the toilet flange is properly secured to the subfloor and sits flush or slightly above the finished floor level. This prevents wobbling and ensures a good seal. “The plumber has to make sure that the subfloor is in good enough condition to secure the flange to prevent wobbling and future leaks,” explains Yaro Didovets of Nadi Plumbing. Elijah from Ajayi Design and Construction adds, “Always check that the flange is level with or slightly above the finished floor to ensure a proper seal.”

Replace old shutoff valves

While you’re prepping the plumbing, consider replacing the shutoff valves. It’s a simple update that can prevent future water issues. “Replace old shutoff valves while you’re there — they’re inexpensive and can prevent future headaches,” advises Elijah.

Choose and place the toilet seal

Next, choose your seal — either a wax ring or a rubber alternative. “Opt for a rubber toilet seal instead of a traditional wax ring for easier adjustments and cleaner removal if needed,” suggests Elijah. On the other hand, Yaro recommends sticking with the classics: “We recommend only wax rings to be used as they are the tried and true method.”

Set the toilet bowl

Lower the bowl carefully over the flange, making sure the bolt holes are aligned. Apply even pressure to compress the seal and prevent leaks. “Press firmly to seal the wax ring, bolt it down evenly to avoid cracking the base,” says Michael Thomsen, owner of City of Oaks Home Repair and Restoration.

Secure the toilet

Tighten the closet bolts evenly, alternating sides to keep the bowl level and protect the porcelain. If there’s any rocking, use shims to stabilize the base. “Alternate sides and apply even pressure to avoid cracking the porcelain base,” recommends Fort Mill Bath Remodel.

Reconnect the tank and water supply

With the bowl in place, attach the tank, install the toilet seat, and reconnect the water supply line. As you do this, consider replacing any old shutoff valves—”preferably with a new quarter-turn valve instead of a gate valve and a new braided supply line, to reduce the risk of leaks and ensure they meet the latest IRC material standards,” recommends Matthew Kraus, CEO of Kraus Remodeling. Once everything is connected, turn the water back on slowly and watch for any signs of leaks.

Test for leaks

Before sealing everything up, give the toilet a few test flushes and check for leaks at the base and water supply. “Always test for leaks before caulking the base,” says Elijah. Poseidon Plumbing adds, “Check for leaks upon completion, but also a few times over the next 24 hours to ensure there are no small drips that may be hard to find.”

Seal the base

Apply a thin bead of caulk around the toilet’s base to prevent water from seeping underneath. Leave a small gap at the back as a leak detection point. “Apply a bead of caulk around the toilet base to prevent water damage, but leave a small gap at the back to help detect any hidden leaks early,” advises Allison Burckel of Inspiration Homes.

Allow time to set

Let the caulk cure for at least 24 hours before using the toilet to ensure a long-lasting, watertight seal. “Let set for at least 24 hours before using to allow setting and drying of caulk,” note Nino and Christina.

Troubleshooting common toilet installation issues

Common issues include leaks, rocking, or a weak flush. Leaks often occur due to an improper wax seal or loose connections. A rocking toilet indicates an uneven floor or inadequate shimming. A weak flush may be due to low water levels in the tank or a malfunctioning flapper. Address these issues promptly to ensure optimal functionality. Double-check all connections and seals.

Maintaining your newly installed toilet

To maintain your new toilet, clean it regularly with non-abrasive cleaners. Avoid flushing items that can clog the drain. Check for leaks and tighten any loose connections. Replace the wax ring periodically to prevent leaks. Routine maintenance ensures the longevity and performance of your toilet. By following these steps, you can keep your toilet in excellent condition.