How to Fix a Toilet Leaking at the Base

Difficulty: Medium • Time: 45 min active, 90 min total • Estimated cost: $10-40 • Safety: DIY-friendly

Overview

A toilet leaking at the base is almost always one of two things: a failed wax ring or loose closet bolts. The wax ring is the soft wax seal between the bottom of the toilet and the drain flange in the floor. It compresses when the toilet is set and creates a watertight, gas-tight seal. Over time — or if the toilet rocks even slightly — that seal breaks, and water seeps out around the base every time you flush.

Here's the critical diagnostic that saves you from pulling the toilet unnecessarily: wipe the base completely dry, lay paper towels around it, and flush. If the paper towels get wet only after flushing, it's the wax ring (water is being pushed past the broken seal). If they're wet even without flushing, the leak is likely condensation on the tank, a supply line drip, or a cracked tank — all of which are easier fixes that don't require pulling the toilet.

Replacing a wax ring sounds intimidating because you have to remove the entire toilet, but the actual job is straightforward: drain, disconnect, lift, scrape, reseal, set back down. The wax ring itself costs $3-8. The most common mistake is not checking the closet flange underneath — if the flange is cracked, corroded, or sitting below floor level (common after a bathroom remodel adds new tile), a new wax ring will fail again within months. This guide covers the flange check and what to do if it's damaged.

Total cost: $10-40 depending on whether you need a flange repair kit. Total time: about 90 minutes for someone who hasn't done it before. A plumber charges $200-350 for this job.

Tools Needed

Adjustable wrench
Putty knife or paint scraper
Hacksaw or mini bolt cutter (for rusted bolts)
Bucket and sponge
Towels (several old ones)
Rubber gloves
Level

Materials Needed

Wax ring with horn (extra-thick recommended) — $3-8
Toilet bolt set (closet bolts + caps) — $5-8
Closet flange repair kit (if flange is damaged) — $10-25
Tube of silicone caulk (optional, for finishing) — $5-8

Step-by-Step Instructions

Confirm the leak is actually from the wax ring: Before you pull the toilet, verify the source. Dry the entire base and floor thoroughly with towels. Lay paper towels or newspaper around the base in a complete ring. Flush the toilet and watch carefully. If the paper gets wet at the base within a few flushes, you have a wax ring failure — proceed with this guide. If the paper stays dry after flushing but you still see water later, check these instead: condensation dripping from the tank (very common in humid climates — touch the tank exterior, if it's cold and wet, that's your culprit), the supply line connection at the bottom-left of the tank (tighten with a wrench), or a hairline crack in the base of the toilet itself (shine a flashlight along the porcelain and look for a wet streak). Condensation is solved with an anti-sweat valve or tank liner kit for $15-20 — no need to pull the toilet.
Shut off water and drain the toilet completely: Turn the shut-off valve behind the toilet clockwise until it stops. Flush the toilet and hold the lever down to drain as much water as possible from both the tank and the bowl. The tank won't refill. Use a sponge and bucket to soak up the remaining water in the tank — get it as dry as you can. Then use the sponge or a wet-dry vacuum to remove standing water from the bowl. The more water you remove now, the less mess when you lift the toilet. This step is not optional; a full toilet weighs 80-100 lbs and will slosh dirty water all over your bathroom floor if you skip draining the bowl.
Disconnect the supply line and remove the toilet: Place towels around the base. Disconnect the water supply line from the bottom of the tank using an adjustable wrench — have a small bucket underneath for the water that drains out. Pop off the decorative bolt caps at the base of the toilet (they pry off with a flathead screwdriver), then unscrew the nuts from the closet bolts. If the nuts are corroded and won't budge, spray them with penetrating oil (PB Blaster or WD-40) and wait 10 minutes. If they're completely seized, cut the bolts with a mini hacksaw — you're replacing them anyway. Once the nuts are off, rock the toilet gently side to side to break the old wax seal, then lift straight up. A standard toilet weighs 50-70 lbs — lift with your legs, not your back, and have a helper if needed. Set the toilet on its side on a flattened cardboard box or old towels.
Inspect the closet flange — this is the step most guides skip: With the toilet removed, you can see the closet flange — the ring bolted or screwed to the floor around the drain opening. Stuff a rag into the drain opening to block sewer gas (do NOT skip this — the smell is immediate and bad). Now examine the flange closely. The top of the flange should sit flush with or slightly above the finished floor surface. If a bathroom remodel added new tile on top of the old floor, the flange may now sit below the floor — this is the #1 reason new wax rings fail. A flange that sits more than 1/4 inch below the floor needs a flange extender ($5-10) stacked on top. If the flange is cracked or has broken bolt slots (extremely common on older plastic flanges), use a flange repair ring that bolts over the top of the existing flange — $10-25 and it provides new bolt slots. Do NOT set the toilet on a damaged flange with a new wax ring and hope for the best; you'll be back in here in 3-6 months.
Scrape the old wax and set new closet bolts: Use a putty knife to scrape all the old wax off both the flange and the bottom of the toilet horn (the round opening on the underside of the toilet). Get it clean — any old wax left behind prevents the new ring from sealing properly. Wipe both surfaces with a paper towel dampened with mineral spirits or rubbing alcohol if the old wax is stubborn. Insert new brass closet bolts into the flange slots, threads pointing up. Position them exactly opposite each other (12 and 6 o'clock). Slide the bolt washers down to hold them upright. The bolts should stand straight up on their own — if they flop over, use a small dab of plumber's putty at the base to hold them in position while you set the toilet.
Set the new wax ring and reinstall the toilet: Place the new wax ring on the flange, centered over the drain opening, with the plastic horn (if it has one) pointing down into the drain. Press it gently into position but don't smash it flat. Remove the rag from the drain. Now comes the critical part: lift the toilet and lower it straight down onto the bolts. You need to land it so both closet bolts come up through the holes in the toilet base AND the toilet horn seats squarely into the wax ring — all in one motion. Eyeball it from above, line up the bolt holes, and lower slowly. Once the toilet contacts the wax, do NOT lift it back up — you'll break the seal and need a new wax ring. Press the toilet down firmly with your body weight, rocking slightly to compress the wax evenly. Place a level across the bowl; if it's not level, use plastic toilet shims (not wood — wood rots) to even it out. Thread the washers and nuts onto the closet bolts and tighten alternately (left side, right side, left side, right side) until snug. Do NOT overtighten — porcelain cracks easily. Snug plus 1/4 turn is enough. If the bolts stick up too far, cut them with a hacksaw and snap the decorative caps on.
Reconnect water, test, and finish: Reconnect the water supply line to the tank. Hand-tighten, then snug with a wrench — 1/4 turn past hand-tight is plenty. Turn the shut-off valve counter-clockwise to restore water. Let the tank fill completely. Flush 3-4 times and watch the base carefully. Lay fresh paper towels around the base one more time and check after 10-15 minutes. No water? You're done. For a clean finish, apply a thin bead of silicone caulk around the base of the toilet where it meets the floor — this prevents water from getting under the toilet if the floor is mopped or splashed. Leave a small gap at the back (nearest the wall) uncaulked so that if the wax ring ever fails again in the future, water will seep out the back where you can see it rather than being trapped invisibly under the toilet and rotting the subfloor. Wait 24 hours before heavy use to let the wax fully conform.

When to Call a Professional

Call a plumber if: the closet flange is severely damaged, corroded through, or the surrounding subfloor feels soft or spongy when you press on it (water damage has been going on longer than you realized and the subfloor may need structural repair before a new toilet can be set); the toilet is leaking from a crack in the porcelain base or tank (not repairable — needs replacement); the drain pipe below the flange is cast iron and visibly corroded or broken (cast iron to PVC transition is real plumbing work); you pull the toilet and discover the flange is set 1 inch or more below the finished floor (a standard extender won't bridge that gap reliably — the flange needs to be raised or rebuilt); or you set the toilet, test it, and it still leaks after two attempts with a new wax ring (the flange or horn alignment is off, and continuing to guess will just waste wax rings). Average plumber cost for a wax ring replacement: $200-350. If the flange needs repair or subfloor work, expect $400-800.