Overview

Swapping an old toilet for a new one is one of the most common bathroom upgrades a homeowner can tackle without a plumber, as long as you're reusing the existing drain flange, shutoff valve, and floor. The job mostly comes down to disconnecting and lifting out the old fixture, cleaning up the flange, and setting the new toilet on a fresh wax ring with new bolts. It's more physical than technical — the toilet is heavy and awkward — but the plumbing connections themselves are simple to make and simple to test for leaks.

Tools & materials

  • New toilet (check the rough-in measurement — usually 12 inches from wall to floor bolts — matches your old one)
  • Wax ring or waxless (foam/rubber) toilet seal
  • New closet (flange) bolts and nuts, with plastic caps
  • New braided supply line
  • Adjustable wrench
  • Screwdriver (Phillips and flathead)
  • Pliers or locking pliers
  • Mini hacksaw (to trim bolts)
  • Utility knife or putty knife (for old caulk and wax)
  • Bucket or old towels and a sponge
  • Old rags (one to stuff in the drain opening)
  • Rubber gloves and safety glasses
  • Plastic shims (to level the new toilet if the floor is uneven)
  • Silicone caulk and caulk gun (for sealing the base after installation)
  • Heavy-duty trash bag for the old toilet

Steps

  1. Turn off the water at the shutoff valve behind or beside the toilet, then flush to drain the tank and hold the flush handle down to clear as much water from the bowl as possible.
  2. Disconnect the supply line from the shutoff valve and the tank with an adjustable wrench, then sponge or bail out any remaining water from the tank and bowl into a bucket.
  3. Remove the nuts from the closet bolts at the base (popping off the caps first), cutting rusted bolts with a hacksaw if they won't turn.
  4. Rock the toilet gently to break the wax seal, then lift it straight up and off the flange — get help or empty the tank first, since a full toilet can weigh 70-120 lbs — and set it on old towels or in a trash bag.
  5. Immediately stuff a rag into the drain opening to block sewer gas, then scrape off the old wax or foam ring and any old caulk from the flange and floor with a putty knife.
  6. Inspect the flange and subfloor around it for cracks, corrosion, or soft/discolored wood before continuing (see When to Call a Pro if you find damage).
  7. Install new closet bolts in the flange slots, remove the rag, and press a new wax ring or waxless seal onto the flange (or the underside of the new toilet's outlet, per the manufacturer's instructions).
  8. Lower the new toilet straight down over the bolts and press down firmly and evenly to compress the seal — avoid rocking or shifting it once it touches down.
  9. Add washers and nuts to the closet bolts and tighten by hand a little at a time, alternating side to side, then snug with a wrench — stop as soon as the toilet is firmly seated; overtightening can crack the base. Trim excess bolt length with a hacksaw and snap on the caps.
  10. Reconnect the supply line, turn the shutoff valve back on slowly, install the tank lid and seat, then flush several times and check the base, tank bolts, and supply connection for any leaks before applying a bead of caulk around the base (leaving a small gap at the back to reveal a future leak).

Safety warnings

  • A toilet can weigh 70-120 lbs — lift with your legs, not your back, and get a helper or separate the tank from the bowl to carry the pieces individually if working alone.
  • Always shut off the water supply and flush to empty the tank and bowl before disconnecting anything, to avoid an unexpected flood.
  • Wear rubber gloves when handling old wax rings, tank water, and bowl water, since it can carry bacteria even after flushing.
  • Keep a rag stuffed in the open drain line whenever the toilet is removed to block sewer gas from entering the room.
  • Hand-tighten closet bolts evenly in small increments rather than cranking one side down fully — overtightening is a common cause of cracked porcelain.
  • Once the new toilet is set onto the wax ring, don't rock, slide, or lift it to check alignment — breaking the seal means starting over with a new ring.

When to call a pro

  • The shutoff valve is corroded, seized, won't fully turn off the water, or drips when closed — don't force it; a stuck or leaking valve should be replaced by a plumber, not worked around.
  • Removing the old toilet reveals a cracked, corroded, or otherwise damaged flange, since a proper flange repair can involve cutting into the drain pipe or subfloor.
  • The subfloor around the flange is soft, spongy, discolored, or smells musty — this points to a long-term leak and possible hidden rot or mold that needs to be addressed before any new toilet is set.
  • The new toilet rocks or won't seat evenly even after shimming, which can indicate an uneven or improperly set flange rather than a simple leveling issue.
  • You notice signs the drain line itself (not just the flange) is damaged, cracked, or improperly sloped — this is major plumbing work beyond a straightforward toilet swap.

Cost estimate

$150-$450 total for most homes: a basic to mid-range toilet runs about $100-$350, plus $20-$40 for a wax ring, closet bolts, supply line, and caulk. Hiring a plumber for installation alone (if you buy the toilet yourself) typically adds $150-$300 in labor.

Sources