How to Fix a Toilet Leaking at the Base

Dry the floor around the toilet completely, then lay a ring of dry toilet paper or paper towels around the base and flush. Paper that wets only during or just after the flush means water is escaping the seal under the bowl — that's a true base leak, and the rest of this guide is your fix. Paper that stays dry while water reappears hours later points to a slow drip from above, so go to step 2 before touching a single bolt.

Most "base leaks" start higher up and just pool at the lowest point. Run a dry paper towel along the supply line and its two connection nuts, around the fill-valve nut under the tank's left side, and across the tank-to-bowl bolts — any dampness there is your real culprit, and a quarter-turn on a compression fitting or new tank bolts fixes it without pulling the toilet. In humid weather, also feel the tank's outside face: a cold, sweating tank drips condensation that looks exactly like a base leak.

Pry the oval caps off the two bolts at the base with a flathead screwdriver and put a wrench on the nuts. Tighten each one a quarter turn at a time, alternating sides, until they're snug — the goal is even, gentle compression of the seal, not torque. If a light snugging stops the leak, you're done for now, but plan on a new seal eventually: a ring loose enough to leak has already been deformed.

Straddle the bowl, grip both sides of the rim, and try to rock it gently side to side. Any movement means the toilet has been flexing the wax ring with every use — rocking is the number-one reason seals fail early, usually because the floor isn't flat under the base. Slide plastic toilet shims into the gaps until the bowl sits dead solid, then trim the shim tails with a utility knife.

Turn the oval shutoff valve behind the toilet clockwise until it stops, then flush and hold the handle down to drain the tank. Sponge or wet-vac the remaining water out of both the tank and the bowl — a dry toilet is several pounds lighter and won't dribble across the bathroom. Disconnect the supply line at the tank, and if the shutoff valve itself weeps or won't fully close, fix that first with our shut-off valve guide.

Unthread both closet-bolt nuts, then lift the toilet straight up off the bolts and set it on its side on an old towel or cardboard. Stuff a rag into the open drain — it blocks sewer gas and catches dropped hardware. Before scraping, read the old wax like a mechanic reads a spark plug: wax squished flat on one side only means the toilet was rocking; wax barely dented anywhere means the flange sits too low to compress it. Then scrape every trace of old wax off the flange and the toilet horn with a putty knife.

A healthy flange sits on top of the finished floor, about a quarter inch proud, with intact bolt slots. Cracked or broken slots get a stainless or brass repair ring screwed down over the old flange — a $10 fix that gives the bolts fresh metal to grip. A flange sitting below floor level (common after new tile or vinyl) gets stacked spacer rings in 1/8- to 3/4-inch sizes, bedded in silicone, or an extra-thick wax ring if it's only slightly low.

Slide new brass bolts into the flange slots, then set your seal: a wax ring goes on the flange (or on the toilet horn) and is strictly one-shot — once the bowl touches down, no lifting for a second try. A waxless rubber seal costs a few dollars more but forgives a missed aim and can be repositioned, which makes it the better pick for a first-timer. Lower the bowl straight down over the bolts, press it home with your full body weight in a slight side-to-side settle, then alternate quarter-turns on the nuts until snug, trim the bolts, and snap on the caps. Our wax ring guide covers this reset in fine detail if you want it.