How to Install a Toilet (2026) — Step-by-Step Guide

Please note: Product availability and information are based on our research at time of writing and are subject to change. This guide is for general reference. Always follow the installation instructions that come with your toilet, and check your local plumbing code before starting.

Introduction

Setting a toilet comes down to a few things done in the right order: a healthy flange, a fresh wax seal, a clean one-motion placement and bolts tightened gently. Most of the risk is in the details. A bowl lowered crooked can distort the seal, and a bolt tightened too far can crack the china.

This guide walks through the whole job for a homeowner with a sound flange, from removing the old toilet to the final leak check. If your flange is cracked, corroded or sitting below the floor, start with our guide to replacing a toilet flange first. If you haven’t bought the toilet yet, our rough-in measuring guide will help you pick one that fits.

Tools and Materials Needed

• New toilet — with its tank hardware and instructions
• New wax seal — see our best toilet wax rings review, or the wax vs. wax-free comparison
• New closet bolts (T-bolts), nuts and washers — if your toilet or flange needs them (see our bolt caps and hardware kits review)
• New supply line — if the old one is worn or the wrong length
• Adjustable wrench and screwdriver
• Putty knife or scraper — for old wax
• Sponge, shop vacuum and towels
• Old rags or cardboard — to set the old toilet on
• Plastic shims — in case the floor is uneven
• Hacksaw — only if a stuck closet bolt won’t come off

Before You Start: Check Three Things

1. Your rough-in and clearances. Rough-in is the distance from the wall to the center of the drain. The new toilet’s rough-in should match your existing one. Plumbing codes also set minimum clearances. Oregon’s adopted code, for example, requires at least 15 inches from the center of the toilet to a side wall or obstruction, and at least 30 inches center to center between fixtures. Your local code may differ, so confirm it.

2. The new toilet. Kohler’s installation guide tells you to inspect the new toilet for damage before you begin. Do this before removing anything, so you find out about a chip or crack while the old toilet is still in place.

3. A shutoff valve. Kohler’s instructions say to install one if your toilet doesn’t have a shutoff valve below the tank. A working valve lets you isolate the toilet without shutting off the house.

Step 1 — Shut Off the Water and Empty the Toilet

Close the shutoff valve. Flush and hold the handle to drain the tank and bowl, then sponge or shop-vacuum out what’s left. Disconnect the supply line from the bottom of the tank.

Step 2 — Remove the Old Toilet

Pry the caps off the two closet bolts, then remove the nuts and washers. If a bolt just spins, cut it with a hacksaw. Rock the toilet gently side to side to break it free of the old wax, then lift it straight up, bending your knees, since it is heavier than it looks. Set it on its side on a towel or cardboard.

Step 3 — Clean and Inspect the Flange

Scrape the old wax off the flange with a putty knife and cover the drain opening with a rag while you work so nothing falls in. Then check the flange. It should be solid, not cracked or corroded, and it should sit at or above the finished floor. Oatey, a flange and wax ring manufacturer, says the flange should sit on top of or even with the finished floor, and that a thicker ring designed for that case can be used if it’s even with the floor. If it sits lower, or if it’s damaged, stop here and follow our flange replacement guide. Press on the floor around the flange as well. If it feels soft or spongy, stop and call a licensed plumber, because that’s a subfloor problem and not a toilet job.

Step 4 — Set the Closet Bolts

Slide new bolts into the flange channel, turn them a quarter turn to lock them, and space them 6 inches apart and parallel to the wall, as American Standard’s instructions specify. Reuse the old bolts only if they’re clean and undamaged.

Step 5 — Place the Wax Seal

Follow your toilet’s own instructions on where the seal goes. Kohler’s instructions press the seal onto the bottom of the toilet around the outlet, while American Standard’s set the ring on the flange with the tapered end facing the toilet. Center it and press it gently so it sits evenly.

Step 6 — Lower the Toilet

Lift the toilet with a helper, line the holes up over the bolts and lower it straight down in one motion, without tipping or twisting. Press down firmly and evenly to compress the seal. Kohler’s instructions add a warning: don’t lift or rock the bowl once it’s placed. If you break the watertight seal, you need a new wax seal, so if you lift it again, reset it with a new one.

Step 7 — Tighten the Nuts Gently

Put a washer and nut on each bolt and tighten them a little at a time, alternating side to side, until the toilet is snug and no longer rocks. Both Kohler and American Standard warn against overtightening because it can crack or chip the china, so stop when the toilet stops moving. Neither manufacturer gives a torque number, so use feel, not force. If the bowl still rocks, slide a plastic shim under the low side, and see our rocking toilet guide if it keeps moving.

Step 8 — Assemble the Tank

Follow your toilet’s instructions for mounting the tank to the bowl, tightening the tank bolts evenly. Kohler’s guide says to check that the tank is level left to right and front to back. Overtightening warnings apply to the tank bolts as well.

Step 9 — Connect the Water and Check for Leaks

Connect the supply line to the fill valve and the shutoff valve according to the line’s instructions, then open the valve slowly. Let the tank fill and check every connection. Flush several times and look for any water at the base and at the supply connection. If the supply line drips, our leaking supply line guide covers the fix.

Step 10 — Finish Up

Trim any long bolt ends if needed, snap on the bolt caps, and wipe up any water. If you haven’t fitted the seat yet, our toilet seat guide takes about ten minutes.

Troubleshooting

The toilet rocks after tightening. Don’t crank the nuts. Add plastic shims under the low side and re-check. See the rocking toilet guide.

Water at the base. The seal may not have seated, or the toilet was lifted after placement. Shut off the water, lift the bowl and reset it with a new wax seal.

The toilet sits too low or too high on the flange. A flange below the floor needs a thicker seal or a flange repair. See the flange guide.

Leak at the supply line. Check that the line is seated and hand-snug, and replace it if the washer or braiding is damaged.

When to Call a Licensed Plumber

• The flange is cracked, corroded or below the floor and you’d rather not replace it
• The floor around the toilet is soft or rotted
• The rough-in doesn’t match any toilet you can buy
• The drain is slow or backing up before you start

Frequently Asked Questions

Q: Can I reuse the old wax ring?

No. Kohler’s instructions say that if the seal is broken after placement you must install a new one, and lifting an old toilet breaks it.

Q: Can I install a toilet by myself?

It’s possible, but American Standard’s instructions recommend two people for handling because the bowl is fragile and heavy.

Q: Should the flange be above or level with the floor?

Oatey says it should sit on top of or even with the finished floor. Below the floor, it’s a repair job.

Q: Wax or wax-free ring?

Both are common. Our comparison covers the differences.

Q: How tight should the bolts be?

Snug, alternating side to side, and stop when the toilet stops rocking. Both manufacturers warn against overtightening.

Conclusion

Installing a toilet is a reasonable job for a careful homeowner: check the flange, set a fresh seal, lower the bowl once, tighten gently and test for leaks. If the flange or floor turns out to be damaged, that’s a different job, and our flange replacement guide or a licensed plumber is the right next step.