How to Install a Toilet

Swapping out a toilet is one of the most satisfying weekend plumbing jobs there is — and one of the most unforgiving if you rush the seal. Get the wax ring and the bolts right and you’ll have a rock-solid, leak-free fixture for decades; get them wrong and you’re looking at a rotted subfloor and a ceiling stain in the room below.

What you’ll need

• Wax ring & closet-bolt kit — the heart of the job; buy a fresh one every time, never reuse
• Basin wrench & putty scraper set — for the cramped supply nut and old wax
• Adjustable wrench — for the tank bolts and supply connections
• Putty knife — to clean the old wax off the flange
• A torpedo or 2-foot level — a rocking toilet is a leaking toilet
• Braided steel supply line — replace the old one while you’re in there
• Quarter-turn shut-off valve — if the old stop is corroded or won’t seal
• 100% silicone caulk — a bead around the base (DAP or GE), plus a caulk gun
• Disposable gloves — the old flange is not a place for bare hands
• Sponge & a bucket — to bail the tank and bowl before you lift
• Optional: a new toilet seat and, if the tank runs, a fill & flush valve kit

Step 1: Shut off the water and drain the old toilet

Turn the shut-off valve behind the toilet clockwise until it stops. Flush and hold the handle to send as much water down the drain as possible, then sponge and bail the rest out of the tank and bowl into a bucket. A dry toilet is dramatically lighter and far less messy to carry.

Pro tip: if the shut-off valve is a round multi-turn handle that’s stiff or weeps when you close it, plan on swapping it for a modern quarter-turn stop now — you already have the water off. It’s a five-minute upgrade that saves you a soaked bathroom the next time you need to isolate the fixture.

Step 2: Disconnect and remove the old bowl

Unthread the supply line at the bottom of the tank with your adjustable wrench. Pry the caps off the two floor bolts and remove the nuts. Break the caulk seal at the base with a utility knife, then rock the toilet gently side to side to free the old wax and lift it straight up. Set it on an old towel or cardboard — it will still drip.

Stuff a rag into the open drain pipe immediately. This blocks sewer gas and, more importantly, keeps a dropped bolt or scraper from disappearing down the line.

Step 3: Scrape the flange clean and inspect it

Pull on your gloves and scrape every bit of old wax off the closet flange with a putty knife until the metal or plastic ring is clean and bare. Now look hard at the flange itself: it should sit on top of the finished floor and be intact. If it’s cracked, badly corroded, or sitting below the floor (common after new tile), stop and fix it with a repair ring or spacer before going further — a wax ring can’t seal to a broken flange.

Step 4: Set the new bolts and wax ring

Drop the two new closet bolts into the flange slots and rotate them a quarter turn so they can’t fall out; slide them to the 3-o’clock and 9-o’clock positions so they line up with the holes in the bowl. Take the new wax ring out of your install kit and press it firmly onto the flange, centered over the drain. Warm wax (leave it in a sunny room for a bit) compresses better than cold. Never reuse an old ring — it’s a one-time seal.

Step 5: Set the bowl and tighten evenly

Lift the bowl, line the two bolt holes up over the closet bolts, and lower it straight down onto the wax without twisting. Once it touches, put your weight on it and rock it slightly to compress the ring — you should feel it settle. Hand-thread a washer and nut onto each bolt, then tighten them a little at a time, alternating side to side, with your wrench.

Common mistake: over-tightening cracks the porcelain and it cracks quietly, so you won’t know until it leaks. Snug is the goal, not gorilla-tight — stop the instant the bowl stops moving. Check it with a level and shim any rock with plastic toilet shims before the final snug.

Step 6: Reconnect water and check for leaks

If your toilet came as a separate tank, bolt it to the bowl now (again, snug and even — the tank-to-bowl gasket does the sealing, not brute force). Connect a fresh braided supply line from the shut-off to the tank, hand-tight plus about a quarter turn. Open the valve slowly, let the tank fill, and flush two or three times while you watch the base, the supply nut, and the tank bolts for any drip. Dry every connection with a rag and check again after ten minutes.

Step 7: Caulk the base and finish

Run a thin bead of 100% silicone caulk around the base of the toilet, leaving a 2-inch gap at the very back. That gap is intentional — it lets you spot a hidden leak instead of trapping water under the bowl. Smooth the bead with a wet finger, snap the bolt caps on, and add a new seat if you’re upgrading. Wipe everything down and you’re done.

Frequently asked questions

Take your time on the seal and this is a job you’ll be proud of every time you walk into the bathroom. If you hit a corroded valve or an odd rough-in and need a part today, your local independent hardware store can hand you the right ring or fitting on the spot — or ask us here and we’ll point you to exactly what fits.