Drip from the faucet spout after shutoff
The faucet keeps dripping from the spout, and turning the hot handle harder may slow it for a while.
Start here: Check the hot faucet cartridge or hot stem first.
Bathroom sink leak
Bathroom Sink Drips Only From Hot Side
Direct answer: If a bathroom sink drips only from the hot side, the leak is usually in the hot handle assembly, hot faucet cartridge or stem, or the hot-side supply connection under the sink. Start by finding the first place that gets wet, not the spot where water finally drips off.
Most likely: Most often, you are dealing with a worn hot faucet cartridge or stem seal if the faucet drips from the spout, or a loose hot handle packing nut or hot supply line connection if the leak shows up around the handle or under the sink.
Run the sink dry, wipe everything down, then test the hot side by itself. Reality check: a drip that shows up on the countertop can start much lower or farther back than it looks. Common wrong move: tightening every nut you can reach before you know which joint is actually leaking.
Don’t start with: Do not start by buying a whole bathroom sink faucet. Hot-side-only leaks usually narrow down fast once you see whether the water starts at the handle, the spout, or the hot shutoff area.
Leak only when the hot handle is opened?Look first at the hot supply line, hot shutoff valve, and the underside of the hot handle.
Drips from the spout even when the faucet is off?The hot faucet cartridge or hot stem is the first suspect, not the drain.
Last reviewed: 2026-04-05
What this hot-side bathroom sink leak usually looks like
Water around the hot handle base
The countertop or faucet deck gets wet near the hot handle when you run hot water.
Start here: Check for a loose packing nut, worn hot handle seal, or water climbing up from below the handle trim.
Water under the sink only when hot water runs
The cabinet stays dry until you open the hot side, then you see drips near the left supply connection or shutoff.
Start here: Check the hot bathroom sink supply line and hot shutoff valve before touching the faucet body.
Drip seems to come from the back of the sink
Water shows up behind the bowl or on the vanity top, but only after using hot water.
Start here: Dry the faucet base and hot handle area completely, then watch for the first bead forming around the hot-side trim or faucet body.
Most likely causes
1. Worn hot faucet cartridge or hot faucet stem
A spout drip that happens with the faucet off is usually water slipping past the hot-side sealing surfaces inside the faucet.
Quick check: Shut the faucet off normally, dry the spout tip, and watch whether a fresh drop forms without using the sink.
2. Loose hot handle packing nut or worn hot handle seal
If water appears around the hot handle only while the hot side is running, the leak is often escaping around the stem area under the handle trim.
Quick check: Run only hot water and look right at the base of the hot handle for the first shimmer of water.
3. Leaking hot bathroom sink supply line connection
A drip under the sink that starts only when hot water is flowing usually points to the hot supply line or its connection nuts.
Quick check: Place a dry paper towel around the hot supply line nuts and open only the hot side for 20 to 30 seconds.
4. Hot bathroom sink shutoff valve seepage
Older shutoff valves can seep at the stem or compression joints, especially after being bumped or partially turned.
Quick check: Feel carefully around the hot shutoff valve body and stem with a dry tissue after running hot water.
Step-by-step fix
Step 1: Pin down whether the first wet spot is above the sink or under it
Hot-side-only leaks usually separate quickly once you know whether the water starts at the handle or at the hot supply connection below.
- Empty the vanity enough to see the hot shutoff valve and hot supply line clearly.
- Dry the faucet, countertop, underside of the sink, hot shutoff valve, and hot supply line with a towel.
- Put a dry paper towel under the hot shutoff area and another around the base of the hot handle.
- Run only the hot side for 20 to 30 seconds, then shut it off and watch both areas.
Next move: You now know whether to stay above the sink at the faucet or move under the sink to the hot supply connection. If you still cannot tell where it starts, use a flashlight and repeat with shorter bursts of hot water while watching one area at a time.
What to conclude: Water at the handle points to the hot-side faucet parts. Water under the sink points to the hot supply line or hot shutoff valve. A spout drip with everything else dry points to the hot cartridge or stem inside the faucet.
Stop if:
- Water is running into the wall, floor, or cabinet seams.
- The shutoff valve will not hold or starts leaking heavily when touched.
- You cannot reach the leak without forcing brittle tubing or corroded fittings.
Step 2: If the leak is at the hot handle, check the easy external fix first
A slight seep at the hot handle is often a loose packing nut or trim area issue, and that is safer to check before taking the faucet apart.
- Turn off the hot bathroom sink shutoff valve under the sink.
- Open the hot handle to relieve pressure, then close it.
- If your faucet has an exposed packing nut below the hot handle, snug it just a small amount clockwise with an adjustable wrench.
- Turn the hot shutoff valve back on and test the hot side again.
- If there is no exposed packing nut or the leak still shows at the handle base, plan on a hot faucet cartridge or hot stem service.
Next move: If the seep stops, the stem area was just loose enough to leak under pressure. If water still appears around the hot handle while running, the hot-side internal seal is worn and the handle assembly needs service.
What to conclude: A handle-base leak that responds to a slight snugging was likely a packing issue. A leak that does not respond usually means the hot faucet cartridge or hot stem seals are worn.
Step 3: If the faucet drips from the spout with the handles off, confirm the hot cartridge or stem is the problem
A spout drip is easy to mistake for a drain or splash issue, but if it happens with the faucet off, the sealing problem is inside the faucet.
- Dry the spout tip completely.
- Leave the sink unused for a minute and watch for a fresh drop.
- Turn the cold side on and off, then the hot side on and off, and notice whether the drip changes after using the hot side.
- If the drip clearly tracks with the hot side, shut off the hot supply and see whether the spout drip stops after pressure bleeds off.
Next move: If the spout drip stops when the hot supply is shut off, the hot faucet cartridge or hot stem is the likely failed part. If the drip continues no matter what, or the faucet is a single-handle style with mixed symptoms, the faucet may need a broader faucet-specific rebuild or replacement.
Step 4: If the leak is under the sink, tighten only the hot-side connection that is actually wet
A small seep at the hot supply line nut is common, and a careful snug can stop it. Random tightening on dry fittings creates new leaks.
- Dry the hot bathroom sink supply line, the hot shutoff valve, and the faucet tailpiece connection above it.
- Wrap a dry tissue around each hot-side joint one at a time and run only hot water.
- When you find the wet joint, use two wrenches if needed so you hold the valve or faucet fitting steady while giving the supply nut a small snug.
- Test again with hot water only.
- If the line itself is wet along its length, kinked, corroded, or still seeps after a careful snug, replace the hot bathroom sink supply line.
Next move: If the joint stays dry through several hot-water tests, the leak was a loose connection. If the same joint keeps wetting or the valve stem itself seeps, the supply line or hot shutoff valve is the better repair path.
Step 5: Make the repair choice based on the leak pattern, then retest before closing the vanity
By this point the leak pattern should be narrow enough that you can fix the right part instead of guessing.
- Replace the hot faucet cartridge or hot faucet stem if the spout drips with the faucet off and the hot side controls the drip.
- Replace the hot bathroom sink supply line if the leak is at the hot line or its end connections and snugging did not solve it.
- Replace the hot bathroom sink shutoff valve if the valve stem or valve body itself is leaking.
- After the repair, dry everything completely and run hot water for one minute, then shut the faucet off and watch for five more minutes.
- Leave the vanity open for the next few uses so you can catch a slow seep before it damages the cabinet.
A good result: If all hot-side areas stay dry and the spout stops dripping, the repair is done.
If not: If the leak source changes or you find water starting at the drain flange instead, move to the bathroom sink drain flange leaking problem instead of replacing more hot-side parts.
What to conclude: A clean retest confirms the first wet point is fixed. If a different area starts leaking, the original drip may have been masking a second problem.
Replacement Parts
Bathroom sink hot faucet cartridge
Bathroom sink hot faucet stem
Bathroom sink hot water supply line
Bathroom sink hot shutoff valve
Repair Riot may earn a commission from qualifying purchases, at no extra cost to you.
FAQ
Why would only the hot side of my bathroom sink leak?
Because the hot side has its own cartridge, stem, seals, supply line, and shutoff valve. If only one side leaks, the problem is usually in that side's parts, not the whole sink.
If the faucet drips from the spout, is it always the hot cartridge?
Not always, but if the drip changes with hot-side use or stops when the hot supply is shut off, the hot cartridge or hot stem is the strongest bet. On some single-handle faucets, the internal mixing cartridge can cause what feels like a hot-side-only drip.
Can I just tighten the hot handle to stop the drip?
You can try a slight snug on an exposed packing nut, but forcing the handle closed is not a real fix. If the spout still drips or the handle base still gets wet, the hot-side internal parts are worn.
Should I replace the whole bathroom sink faucet?
Not first. If the leak is clearly at the hot cartridge, hot stem, hot supply line, or hot shutoff valve, fixing that part is usually the cleaner move. Whole faucet replacement makes more sense when the faucet body is cracked, badly corroded, or the internal parts are no longer practical to match.
What if I find the water is really coming from the drain area instead?
Then stop chasing the hot side. A leak that starts at the drain flange or pop-up area needs a different fix path, even if you only noticed it while running hot water.