You repair a toilet leak by finding which part leaks: tighten or replace a supply line, replace the tank bolt washers or the tank to bowl gasket, replace a flapper or fill valve for an internal leak, or reset the toilet on a new wax seal for a leak at the floor. A cracked tank or bowl cannot be repaired and the toilet is replaced. Our toilet repair page lists the parts.
If you are not sure where the water comes from, the plumber for toilet leak page walks through the paper towel test.
Which toilet leaks can you repair yourself?
You can repair leaks at the supply line, at the tank bolts, and inside the tank from a worn flapper or fill valve. Each uses basic tools and cheap parts. Leaks at the floor, from a cracked tank or bowl, or from anything that needs the drain opened, are plumber jobs or a replacement.
Match the symptom to the repair:
| Symptom | Likely cause | Repair |
|---|---|---|
| Drip at the wall valve or hose | Loose nut or worn supply line | Hand-snug the nut, replace the line |
| Water under the tank after a flush | Tank bolt washers or tank gasket | Replace washers or gasket, tighten bolts evenly |
| Tank refills with nobody flushing | Flapper or fill valve | Dye test, then see the flapper or fill valve pages |
| Water at the base | Wax seal or flange | Plumber lifts and reseals the toilet |
| Water from a visible crack | Cracked porcelain | Replace the toilet |
| Sweating on the tank | Condensation | Dry it, ventilate, see if it returns |
Start by closing the shut off valve and drying everything. Lay dry paper towel on the floor and around each joint, and flush once. The wet towel tells you the source.
How do you repair a leaking toilet tank?
If water drips from the underside of the tank, the cause is usually the two tank bolts and their rubber washers, or the large rubber gasket where the tank meets the bowl. Drain the tank, replace the washers or the gasket, and tighten the nuts evenly. If the tank itself is cracked, no fix holds, and the toilet is replaced.
Steps for a tank bolt repair:
- Close the shut off valve, flush and sponge out the tank.
- Disconnect the supply line at the tank.
- Hold each bolt head inside the tank with a screwdriver and loosen the nut underneath with a wrench.
- Lift the tank off the bowl, set it on a towel, replace the bolt washers and the gasket, and set it back.
- Tighten the nuts a little at a time, alternating sides. Too much force cracks the tank.
Look at the tank closely before you do all this. A hairline crack that runs the height of the tank, or a chipped area near a bolt hole, means that repair will not last. Some leaks are not leaks at all. A cold tank in a humid bathroom sweats. If the water is only on the outside surface, wipe it dry and see if it returns when the toilet is not flushed.
An inside leak is different: EPA WaterSense says a leaking toilet could waste about 200 gallons a day, so a quiet tank leak matters even when the floor stays dry.
How do you fix a toilet leaking at the base?
A toilet leaking at the base needs a new wax ring or foam seal between the bowl and the floor flange. Shut off the water, drain the toilet, unbolt it, lift it away, clean the flange, fit a new seal and reset the toilet level, then tighten the bolts evenly. Check the flange and subfloor while the toilet is off.
This is the repair where a plumber earns their fee. A toilet is heavy and awkward to lift without cracking the base, and a seal set crooked leaks again within weeks. The plumber also checks for a loose bowl, a cracked flange, and soft wood in the floor. If the subfloor is damaged, a carpenter has to repair it before the toilet is reset.
Do not caulk around a leaking base to hide a leak. Caulk can trap water under the toilet and hide the first warning sign of a failing seal.
When is it time to replace a leaking toilet, not repair it?
Replace the toilet when the tank or bowl is cracked, when the glaze is crazed and leaking, when repeated repairs keep failing, or when the toilet is an old high-volume model that costs more in water than a new one would. In California, the water use rules may also decide the question.
California Civil Code sections 1101.1 to 1101.9 set rules for plumbing fixtures in buildings built on or before January 1, 1994. A toilet using more than 1.6 gallons per flush counts as noncompliant under the law, and when a building is altered, noncompliant fixtures have to be replaced with water-conserving ones. For toilets, local certification forms generally require 1.28 gallons per flush. Whether the rules apply to your repair depends on whether you are altering the building and getting a permit, so ask the City of Los Angeles building department, LADBS, if you are unsure.
Water agencies pay for the switch. LADWP lists premium high-efficiency toilets among its residential rebates. Amounts and rules change, so check the current offer on the LADWP rebates page before you buy. A new toilet could be partly paid for. See what a toilet replacement costs for the install ranges.
What does it cost to repair a leaking toilet?
Angi puts the average toilet repair in Los Angeles at about $290, with a typical range of $151 to $429, and puts a leaky toilet at $115 to $685 depending on the cause. Supply line and washer fixes sit at the bottom, while a reseal or a tank replacement sits near the top.
Parts are cheap: a supply line, bolt washers or a flapper cost a few dollars to $25, and a fill valve $10 to $40. What you pay a plumber for is the diagnosis and the time on site. A written quote before work starts keeps it clear. If the answer is a new toilet, the plumber should say so before touching the old one.
If you would rather not guess which part is failing, use the quote page. We'll arrange a local plumber to come to you. Read how a job runs for the steps from message to finished repair. City of Angels Plumbing covers the whole city.
Common questions
How long does it take to repair a toilet leak?
Supply line and washer repairs take under an hour. A reseal at the base takes longer because the toilet has to come up and be set again. If the floor is damaged or the toilet is replaced, expect a longer visit. A plumber can give you a time estimate once they see the leak.
What should I ask before I hire someone to repair a toilet leak?
Ask which part is leaking, whether the quote includes a new seal and bolts, and whether they check the flange and subfloor. Ask what happens if the toilet turns out to be cracked, and what the service call fee includes. If the job is large, ask for their CSLB license number.
Does someone need to be at the property?
Yes, or an adult you trust, so the plumber can get to the bathroom and the water shut off. If the leak has damaged a floor or a ceiling below, show the plumber the damage and take photos for your records.
Can I use sealant or tape to stop a toilet leak?
Not for a lasting fix. Plumber's tape belongs on threaded joints, not on porcelain. Sealant on a cracked tank or bowl does not hold, and caulk around the base hides a failing seal. Identify the leaking part, then replace it or the toilet.
Is a leaking toilet covered by a water bill adjustment?
That depends on the utility and its current rules, so there is no standard answer. If a leak raised your bill, call LADWP customer service and ask whether any adjustment applies. Keep the repair invoice and a photo of the repaired part in case they ask for proof.