What are expert tips for toilet installation steps?

Sit on the toilet to set the wax seal -- your body weight provides more even pressure than pushing with your hands. Use a braided stainless steel supply line, not a plastic one. They're $5 more and won't burst. If the toilet rocks even after tightening, use plastic toilet shims (not wood). Trim the shims flush with the base and caulk over them. Caulk the base of the toilet to the floor on the front and sides, but leave the back open. That way if the wax seal ever fails, water seeps out the back where you'll see it instead of being trapped under the toilet.

What mistakes should I avoid with toilet installation steps?

Overtightening the closet bolt nuts and cracking the porcelain base. Rocking the toilet while setting it on the wax ring -- this breaks the seal. Not checking the rough-in distance before buying the toilet. Reusing the old wax ring, closet bolts, or supply line.

Toilet Installation Steps | The Plumbing Directory

Overview

Installing a toilet is one of those jobs that sounds intimidating but is actually pretty straightforward. You're basically setting a heavy thing on two bolts, connecting a water line, and making sure the seal is good. The whole job takes 1-2 hours, and the only part that gets messy is removing the old toilet. If you can lift 50-60 pounds and turn a wrench, you can do this.

What to Know

Before You Start

Buy a new wax ring (or wax-free seal), new closet bolts, and a new supply line. Don't reuse any of these -- they're cheap and a failed seal or supply line is not worth saving $5. Also check your rough-in distance: measure from the wall (not the baseboard) to the center of the closet bolts. Standard is 12 inches, but older homes may have 10 or 14 inch rough-ins.

One-Piece vs Two-Piece

Two-piece toilets (separate tank and bowl) are lighter and easier to maneuver. One-piece toilets look sleeker but weigh 80-100+ pounds and are awkward to position alone. If you're doing a one-piece, get a helper for the set.

Tools & Materials

Adjustable wrench
Putty knife (for old wax ring)
New wax ring or wax-free seal
New closet bolts
New supply line (braided stainless)
Bucket, towels, and rags
Level
Hacksaw (for trimming closet bolts)

Step by Step

Shut off water and drain the old toilet
Close the shutoff valve behind the toilet. Flush and hold the handle to drain as much water as possible. Sponge out the remaining water from the tank and bowl. Disconnect the supply line from the tank.
Remove the old toilet
Pop the bolt caps and unscrew the closet bolt nuts. Rock the toilet gently to break the wax seal, then lift it straight up. It's heavy and full of residual water -- have towels ready. Stuff a rag in the drain opening to block sewer gas.
Clean the flange and inspect
Scrape the old wax ring off the flange with a putty knife. Inspect the flange for cracks, rust, or damage. If the flange is below floor level, you'll need a flange extender. If it's cracked, see the flange repair article.
Set new closet bolts and wax ring
Insert new closet bolts into the flange slots and make sure they're centered and vertical. Place the new wax ring on the flange (rounded side up). Or if using a wax-free seal, press it onto the bottom of the toilet outlet.
Set the toilet
Remove the rag from the drain. Lift the toilet and lower it onto the closet bolts, aligning the holes in the base with the bolts. Press straight down with firm, even pressure. Don't rock it side to side -- you'll distort the wax seal. Sit on the toilet to compress the seal with your body weight.
Bolt down and level
Thread the nuts onto the closet bolts and tighten alternately, a little at a time on each side. Don't overtighten -- the porcelain can crack. Snug enough that the toilet doesn't rock. Check for level. Shim if needed, then caulk around the base.
Connect tank (two-piece) and supply line
For two-piece toilets, set the tank on the bowl with the gasket in place and tighten the tank bolts evenly. Connect the braided supply line from the shutoff valve to the tank fill valve. Hand-tight plus a quarter turn.
Test
Turn on the water slowly. Let the tank fill. Flush several times. Check around the base for any water seeping from the wax seal. Check the supply connection and tank bolts for drips.

Pro Tips

Sit on the toilet to set the wax seal -- your body weight provides more even pressure than pushing with your hands.
Use a braided stainless steel supply line, not a plastic one. They're $5 more and won't burst.
If the toilet rocks even after tightening, use plastic toilet shims (not wood). Trim the shims flush with the base and caulk over them.
Caulk the base of the toilet to the floor on the front and sides, but leave the back open. That way if the wax seal ever fails, water seeps out the back where you'll see it instead of being trapped under the toilet.

Mistakes to Avoid

Overtightening the closet bolt nuts and cracking the porcelain base.
Rocking the toilet while setting it on the wax ring -- this breaks the seal.
Not checking the rough-in distance before buying the toilet.
Reusing the old wax ring, closet bolts, or supply line.

When to Call a Pro

If the flange is broken, severely corroded, or significantly below floor level, a plumber can repair or replace it properly. Also call a pro if you're moving the toilet to a different location, which requires moving the drain pipe in the floor.

Bottom Line

Toilet installation is a 1-2 hour job that saves $150-$350 in labor. New wax ring, new bolts, new supply line. Press straight down (don't rock), tighten evenly, and caulk the base. That's the whole job.

Toilet Installation Steps