Replacing a toilet is a very doable DIY job that upgrades comfort and water efficiency. The whole task hinges on one thing: a clean, leak-free seal at the floor flange.
Remove the old toilet
Shut off the supply valve, flush, and sponge out the remaining water. Disconnect the supply line, unbolt the toilet from the floor, and rock it free. Plug the drain opening with a rag to block sewer gas while you work.
Prep the flange
Scrape off the old wax ring and inspect the flange. A cracked or sunken flange needs repair or a repair ring first — setting a toilet on a bad flange is the top cause of leaks.
Set the new toilet
Place a new wax ring, lower the toilet straight down onto the bolts, and press to seat it. Don't rock it once it's set or you'll break the seal. Snug the bolts evenly — firm, not overtight, or you'll crack the porcelain.
Connect and test
Reconnect the supply, turn the water on, and flush several times while watching the base for leaks. Caulk around the base, leaving a gap at the back so a future leak shows rather than hides.