When a sink won’t drain, clear the trap, plunge, and flush the line; avoid harsh chemicals and check the disposal and vent.
If the basin fills and stays there, you’re most likely dealing with a clog near the basket strainer, a packed P-trap, a jammed disposer, or a venting issue. This guide walks you through fast checks first, then the reliable fixes a homeowner can do in under an hour, plus when to call a pro.
Fast Diagnosis And First Moves
Before grabbing tools, run through a quick triage. These checks often free the blockage without tearing anything apart.
| Symptom | Likely Cause | First Fix |
|---|---|---|
| Standing water on both sides of a double-bowl kitchen sink | Clog at the shared drain or just past the tee | Plunge one side with the other tightly plugged; then flush hot water |
| Gurgling or slow return after draining | Vent restriction or partial blockage downline | Plunge, then run a small auger; if repeat gurgles, inspect roof vent |
| Disposer hums or trips and water backs up | Jammed disposer or overload trip | Cut power, free the jam with hex key, press reset, test |
| Bathroom sink drains slowly and smells musty | Hair and biofilm in the trap and tailpiece | Remove trap, hand-clean, brush the pipe, reassemble |
| Backed-up sink after greasy cooking | Fats and oils congealed in the line | Physically remove with auger/cleanout; avoid pouring chemicals |
Safety First: What Not To Do
Skip mixing cleaners. Bleach with ammonia or acids can release hazardous fumes. Keep windows open, wear gloves, and stick to one product at a time if you must try a cleaner.
If your home uses a septic tank, steer clear of aggressive chemical openers. They can disrupt the tank’s biology and push problems downstream. Gentle mechanical methods (plunger, hand auger) are safer for drains and septic systems.
Gather The Basics
You don’t need a full plumbing shop. A few simple tools will carry you through most blockages.
- Cup plunger (sink style with a flat rim)
- Bucket and old towels
- Channel-lock pliers and a small adjustable wrench
- Plastic zip strip or hair snake for bathroom sinks
- Hand auger (¼-in. cable) or a drum snake for kitchen lines
- Hex key (Allen) for common disposers, and a flashlight
Step-By-Step: Clear A Kitchen Sink
1) Prep The Work Area
Remove standing water with a cup into a bucket so your plunger can grab. If it’s a double bowl, plug one side with a tight drain stopper or a wet rag to keep pressure focused.
2) Plunge With A Tight Seal
Place the cup over the drain, add a little water to cover the rim, and press firmly. Give 10–15 steady strokes. Lift quickly to see if water moves. Repeat a few cycles. If the bowl drains and then stalls again, you loosened the clog; go again or move to an auger.
3) Check The Disposer (If Present)
Kill power at the switch or breaker. Shine a light inside; remove any foreign object with tongs. Turn the motor hub with the hex key in the bottom socket to free tight spots. Press the red reset button underneath, restore power, and run cold water while testing. If it trips again, leave it off and proceed to the trap.
4) Clean The P-Trap
Place a bucket under the trap. Loosen the slip nuts by hand or with pliers and ease the trap off. Expect a splash. Empty it, scrub out grease or debris, and check the trap arm and wall stub with a bottle brush. If the trap is clean but you still have a blockage, the clog sits further down the branch line.
5) Run A Hand Auger
Feed the cable into the wall stub until it meets resistance. Lock the set screw and crank while pushing gently. When the cable grabs, keep turning to break the clog. Retract and wipe the cable, then send it again. Reassemble the trap with new washers if the old ones are brittle. Run hot water to flush.
Bathroom Sink Not Draining? Try This Flow
1) Pull The Stopper
Under the basin, loosen the nut on the pivot rod and slide the rod out to free the stopper. Lift the stopper; hair mats often sit right there.
2) Scrape And Brush
Use a plastic zip tool to pull hair from the tailpiece. Brush the tailpiece and trap. Rinse each part in a bucket, not the sink. Reinsert the stopper, reconnect the pivot rod, and snug the nut without overtightening.
3) Flush Test
Run hot water for a minute. If it still pools, remove the trap and snake from the wall toward the branch line, same as with a kitchen sink.
When The Vent Is The Culprit
Drain lines need air to prevent vacuum lock. If you hear constant glug-glug sounds or see water pull down other traps when one fixture drains, the vent stack may be restricted by leaves, a bird nest, or frost. From the roof, you can look down the vent—only if it’s safe to do so. A garden hose set to a gentle flow can confirm a blockage; a pro can clear it with a proper auger from above. If roof access isn’t safe, stop and book a licensed plumber.
Cleaner Choices That Don’t Hurt The System
Chemical openers promise speed, but they’re rough on finishes, gaskets, and sometimes you. A mechanical approach clears the line without caustics, and it’s kinder to septic setups.
| Method | Best Use | Notes |
|---|---|---|
| Plunger | Fresh clogs near the strainer or tee | Seal matters more than force; plug the second bowl on kitchen sinks |
| Hand auger (¼-in.) | Hair, soap scum, food bits in branch lines | Feed gently and keep turning; protects traps and finishes |
| Drum snake or power auger | Stubborn grease or long branch runs | Great for kitchen lines; mind cable control to avoid kinks |
| Enzyme/bacterial maintenance | Ongoing prevention after a clear | Use overnight per label; maintenance, not a fix for hard clogs |
| Caustic/acid cleaners | Last resort only | Tough on metals and seals; avoid around septic and with disposers |
Sink Not Draining? Causes And Fixes In Detail
Grease And Food Paste
Cool fats congeal and grab crumbs. Over time the inner pipe wall narrows like a clogged artery. Once it sets, only an auger or a proper cleanout will restore full flow. Grease belongs in the trash, not the drain; wipe pans with a paper towel before washing.
Hair And Soap Film
In bathrooms, hair twists with soap scum into rope-like strands. A $3 plastic strip tool removes most of it in seconds. Follow with a hot water flush to wash away loose film.
Disposer Jams
Peach pits, coins, or fibrous peels can lock the grind ring. Power off, free the jam with the hex socket on the bottom, press the reset button, and test with cold water running. If it hums without spinning, leave it off and call a pro to avoid motor damage.
Scale And Old Galvanized
In older homes, galvanized steel can choke with mineral scale and rust. Snaking helps only for a while; long-term relief is a section of new drain pipe in PVC or ABS. That upgrade is a plumber’s job.
Vent Restrictions
If traps burp and drains pull slow across multiple fixtures, suspect the vent. Windblown debris and small animals cause common blockages. Clearing a roof vent is quick for a pro with the right gear and ladder safety.
Pro Tips That Save Time
- Seal beats muscle: When plunging, smear a bit of petroleum jelly on the cup rim for a better seal.
- Protect finishes: Lay a towel in the cabinet and use a second one over tools to avoid scratching chrome.
- Mind the washers: Re-use slip-joint washers only if they’re supple. If they’re flattened or cracked, replace them.
- Label trap parts: Snap a quick photo before disassembly so every piece returns to the same orientation.
- Flush hot: After clearing a kitchen clog, run hot water for two minutes to carry residue out to the main.
When To Call A Plumber
Get help if you’ve snaked 15–20 feet with no improvement, if water backs up into nearby fixtures, or if you suspect a collapsed line. Recurrent backups in the same spot point to a sagging pipe section or a deeper obstruction that needs a camera inspection.
Simple Prevention That Works
- Use a mesh strainer in every sink and empty it into the trash daily.
- Wipe greasy pans before washing; pour cooled fats into a lidded container and toss.
- Once a month, pull the bathroom stopper and clear hair before it mats.
- Run cold water while the disposer is on, and a few seconds after switching it off.
- Every few months, treat drains overnight with an enzyme cleaner to keep biofilm in check.
Reference Notes You Can Trust
Never mix bleach with other cleaners; stick to a single product and ventilate well. For households on septic, mechanical clearing beats harsh chemicals. For disposers that stop mid-job, clearing the jam and using the reset button is the right move. These practices align with guidance from public-health and environmental agencies as well as manufacturer instructions (linked above in the body).
Quick Win Checklist
- Empty the basin and plunge with a tight seal.
- Kill power, free and reset a stuck disposer.
- Pop the trap into a bucket, clean, and reassemble.
- Snake the wall stub until the cable runs freely.
- Flush hot water and install a strainer to prevent repeat clogs.
Heads-up: Bleach and ammonia don’t mix. If you need a refresher on safe use, see the CDC’s guidance linked in the Safety section. Septic households should stick to mechanical methods; the EPA page linked earlier explains why. And if a disposer trips, the maker’s reset steps are the safe route.