Toilet Leaking From the Bottom? Rule Out the Supply Line First
Water at the base often comes from the supply line, the tank bolts or a sweating tank, not the floor seal. Test in order, then fit a braided line if it drips.
By Jamilur Rahman Updated November 5, 2026 · 7 min read
- Time
- 30 min
- Cost
- Under $20
- Difficulty
- Medium
In this guide
Quick answer
Water around a toilet base comes from one of four places: the supply line, the tank bolts, condensation on the tank, or the seal under the bowl. Dry everything and test in that order, because the supply line is the cheapest to check and fix. If it drips, replace it with a braided stainless line in about 15 minutes.
Free fix vs. permanent fix
Dry everything and find the drip
- Dry the floor, tank, pipes and base with a towel
- Wrap dry tissue around each connection
- Wait 15 minutes, flush once, and see which tissue gets wet
- Do not guess, because a wet floor can hide the real source
How long it lasts: Finds the source for free. Snugging a loose nut can stop a slow drip for a while, but a worn washer or cracked line will keep leaking.
A braided stainless steel supply line
A line that drips at a nut has a worn washer or a cracked body, and cranking the nut harder often makes it worse. A new braided line starts with fresh seals and a flexible, kink-resistant body, so the connection is dry. It only fixes a supply leak, which is why the tests come first.
What to get: Braided stainless steel toilet supply line
How long it lasts: Years. The steel braid guards against bulging and kinks, and the nuts come with fresh seals.
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What you'll need
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Towel and small bucket
For drying and for catching water from the line
You have it -
Toilet paper or dry tissue
Shows where water really comes from
You have it -
Adjustable wrench
For the supply nuts, a quarter turn at most
You have it - Our pick Illustration
Braided stainless steel toilet supply line
The usual fix if the tissue gets wet at the supply nuts
- Illustration
Tank-to-bowl bolt and gasket kit
Only if the tank bolts are wet
- Illustration
Toilet wax ring kit
Only if the floor seal is the leak
Why it happens
A loose or worn supply line connection
Water drips from the nut at the shut-off valve or the one under the tank, then runs down to the floor. Old washers dry out, and kinked or plastic lines crack.
Leaking tank bolts or the tank-to-bowl gasket
Bolts inside the tank hold it to the bowl. A worn rubber washer lets water run down the outside of the bowl, so it looks like a base leak.
Condensation on a cold tank
In warm, humid air the cold tank grows beads of water that run down the bowl. It looks like a leak, but it is even on all sides and is worst in summer.
A failed wax ring seal
The seal between the bowl and the floor flange can fail, often after the toilet has rocked. Water seeps out at the base, mostly after flushing, and sewage may smell.
A cracked bowl or tank
This is rare. A hairline crack leaks steadily and usually means replacing the toilet.
Try this first (free)
Do these in order, starting with the simplest.
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1. Dry everything
Tool used: Towel and small bucketMop the floor, then dry the tank, bowl, supply line, shut-off valve and base. Only a dry surface shows the real drip.
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2. Wrap tissue around each joint
Tool used: Toilet paper or dry tissueWrap dry toilet paper around the nut at the shut-off valve, the nut at the tank and each tank bolt. Put a strip on the floor around the base. Wait 15 minutes, then flush once. The first tissue to get wet shows the source.
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3. Snug the supply nuts
Tool used: Adjustable wrenchIf a nut is wet, tighten it a quarter turn by hand or with a wrench. Over-tightening can crack the plastic or crush the washer. If it still weeps, replace the line.
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4. Replace the supply line
Tool used: Braided stainless steel toilet supply lineClose the shut-off valve, flush and hold the handle to empty the tank. Put the bucket under the line and unscrew both nuts. Fit the new braided line, hand-tight plus a quarter turn, then turn the water on slowly. Check each joint with fresh tissue. Take the old line to the store to match the ends.
IllustrationCheck price on AmazonTool for this step
Braided stainless steel toilet supply line · The usual fix if the tissue gets wet at the supply nuts
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5. Read the rest of the clues
Wet tank bolts mean new bolt washers. A tank beaded with water in humid weather, with dry joints, is condensation. If only the bottom of the bowl is wet after a flush, the floor seal is the suspect.
When free fixes aren't enough
If the supply line stays dry and the water shows at the base after a flush, the wax ring is the likely culprit. That means lifting the toilet. A bowl is heavy, so get help or call a plumber, especially if you smell sewage, see stains or the floor feels soft. A wax ring leak can soak into the subfloor and cause rot and mold for months before you see it. If wastewater is leaking, stop using the toilet until it is sealed. If water is spraying from the line, shut off the main.
Buy the fix
Still stuck after the free fixes? These are the products we would look at.
| Pick | Product | Fixes | Who it's for | Buy |
|---|---|---|---|---|
| Best pick | Braided stainless steel toilet supply line | a drip from the supply line or its nuts | Anyone whose supply line is wet, old, kinked or made of thin plastic. | Check price |
| Budget pick | Tank-to-bowl bolt and gasket kit | water dripping from the tank bolts down the outside of the bowl | Anyone whose tissue gets wet at the tank bolts. | Check price |
| Upgrade pick | Toilet wax ring kit | a leak at the floor seal under the bowl | Handy people who have confirmed the base leaks after a flush and can lift a heavy toilet with help. | Check price |
Braided stainless steel toilet supply line
Fixes: a drip from the supply line or its nuts
Look for: Ends that match your shut-off valve and fill valve, where 3/8 inch compression and 7/8 inch ballcock are common, so check yours; A length that reaches with a gentle curve and no kink; A washer already seated in each nut.
- Who it's for
- Anyone whose supply line is wet, old, kinked or made of thin plastic.
- Honest downside
- The line is dry. Do not replace parts that are not leaking, and test first.
Tank-to-bowl bolt and gasket kit
Fixes: water dripping from the tank bolts down the outside of the bowl
Look for: Brass or stainless bolts that will not rust; Rubber washers for inside and under the tank; A gasket or seal that fits your toilet.
- Who it's for
- Anyone whose tissue gets wet at the tank bolts.
- Honest downside
- Your tank is sweating, not leaking. A new gasket will not stop condensation.
Toilet wax ring kit
Fixes: a leak at the floor seal under the bowl
Look for: A ring that matches your flange height, standard, extra thick or wax-free; Closet bolts and washers included.
- Who it's for
- Handy people who have confirmed the base leaks after a flush and can lift a heavy toilet with help.
- Honest downside
- The floor is soft or the flange is broken. Call a plumber.
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How we picked: How we picked: this page is based on toilet leak-diagnosis guides, supply line and wax ring maker instructions, and the problems and fixes people report in owner reviews. We do not test products by hand.
How to size a new supply line
Check three things. The shut-off valve outlet, where 3/8 inch compression is common. The thread on the fill valve, where a 7/8 inch ballcock nut is typical. And the distance between them, measured with a string, with a few extra inches so the line curves instead of kinking. If you are unsure, take the old line to the store.
When to stop and call a plumber
- The floor feels soft or spongy near the base
- You smell sewage
- A ceiling below the bathroom is stained
- Water appears at the base after every flush, and the supply line is dry
What to skip
Caulking the base to stop the leak
Caulk cannot hold back a leak under drain pressure. It can trap water under the toilet, hide the problem and rot the floor. Find the source first. Stuffing towels around the base does the same, and it hides the damage.
Frequently asked questions
Why is there water around the base of my toilet?
Why does my toilet leak only when I flush?
Is a leaking toilet base an emergency?
How do I tell condensation from a leak?
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