A drain full of standing water is a particular kind of problem. You can’t see the clog, you can’t use most drain products, and every DIY tip online seems to assume the water has already gone. This guide walks through clearing a clogged sink, tub or shower that’s holding standing water, safely and in the right order.
It also covers the one check you should do before anything else. If the standing water isn’t really your drain’s problem, none of the steps below will help.
First: is it one drain, or the whole house?
Before you start, run water briefly at one other fixture, or flush a toilet once, and watch the drain that’s full.
- If nothing changes, it’s a clog in that one fixture. Carry on with the steps below.
- If the water level in the clogged drain rises, or another drain gurgles or backs up, the blockage is in the main line, not the fixture. Stop using water and skip to the section on main-line problems.
In condo and apartment buildings, there’s a third case. If you’re on a lower floor and your kitchen sink fills when neighbours above run water, the problem is a shared vertical stack. That’s common in multi-storey buildings around Torrey Pines and UTC, and it needs the building’s stack cleared, not your sink.
What you’ll need
- Rubber gloves
- A small container or cup, and a bucket
- Old towels
- A cup plunger (for sinks, tubs and showers) or a flange plunger (for toilets)
- A plastic drain-cleaning strip or a hand-held drain snake
- An adjustable wrench (for sink traps)
- A wet/dry vacuum, if you have one
Step 1: Don’t add anything to the water
Don’t pour in chemical drain cleaner. With standing water, the cleaner is diluted and can’t reach the clog properly. When it fails, you’re left with a basin of caustic water that will splash on you when you plunge, and burn whoever opens the trap next. It’s also hard on old cast-iron pipe, which many La Jolla homes have.
Don’t pour in boiling water either. It can soften PVC pipe joints, and it can crack a porcelain sink or toilet bowl.
Step 2: Remove most of the water
Bail the standing water into a bucket with a cup or small container. Leave about an inch or two in the bottom. That’s enough to help a plunger seal, but not so much that it splashes everywhere.
A wet/dry vacuum makes this quick. For a toilet, bail down to the normal water level.
Step 3: Pull out what you can reach
- Bathroom sink: remove the pop-up stopper. On most sinks it lifts straight out, or comes out after you loosen the pivot nut under the sink. Clean off the hair and gunk.
- Tub: remove the stopper or trip-lever plate on the overflow, and pull the linkage out. Hair often wraps around it.
- Shower: unscrew or pop out the strainer.
Then feed a plastic drain strip down the drain, twist and pull up. In bathrooms, this alone often clears the drain. Near the beach, you may also find sand. Our guide to clearing a shower drain clogged with sand and hair covers that in detail.
Step 4: Plunge properly
Most people plunge wrong. Here’s how to do it right.
- Block any overflow. Bathroom sinks and tubs have an overflow opening. Stuff a wet cloth into it, or the plunger will just push air out of the overflow.
- For a double kitchen sink, block the other drain with a wet cloth or second plunger.
- Seal the plunger over the drain, with water covering the cup.
- Push gently first to get the air out, then use 10 to 15 firm, quick strokes, keeping the seal.
- Pull off sharply on the last stroke. The suction pull often does more than the push.
Repeat two or three times. If the water starts to drop, run hot tap water for a minute to clear the remaining debris.
Step 5: Clean the trap (sinks only)
If the sink still won’t drain, the clog is probably in the trap, the U-shaped pipe under the sink.
- Put a bucket and towels underneath. There will be water in it.
- Loosen the two slip nuts by hand or with a wrench.
- Remove the trap and empty it into the bucket. Clean it out.
- Look into the trap arm going into the wall. If you can see a clog, a hand snake will reach it.
- Reassemble and hand-tighten. Run water and check for leaks.
Step 6: Use a hand snake
If the trap was clear, the clog is in the branch line behind the wall or under the floor.
- Feed the snake into the drain (or the trap arm, with the trap removed).
- When you feel resistance, lock the cable and turn the handle clockwise while pushing gently.
- You’ll feel it either break through or catch something. Pull it back slowly and clean off what you’ve caught.
- Run hot tap water to test.
A 25-foot hand snake reaches most branch-line clogs in a single-family home. Don’t force it. If it won’t go further, stop.
When to stop and call a plumber
Stop if:
- the water won’t drop after plunging and cleaning the trap,
- the snake meets a hard stop it can’t get past,
- you see water coming up in another fixture,
- the drain smells strongly of sewage,
- or the same drain has clogged several times recently.
A single fixture clog is $180 to $275 for us to clear, and booking online takes $49 off. See our clogged drain repair page for per-fixture prices.
When it isn’t your drain
If standing water appears in a shower or tub when you flush a toilet, or several drains are holding water at once, the blockage is in the main sewer line. That’s a different job, with different tools, and DIY methods won’t reach it.
What to do:
- Stop using water everywhere in the property. Every flush or sink you run adds to the backup.
- Don’t plunge a drain that’s backing up from the main line. You’ll just push sewage around.
- Keep people and pets away from any backed-up water. Treat it as contaminated.
- Cut power at the breaker if water is near outlets or appliances.
- Call. If wastewater is entering the house, it’s an emergency. We dispatch 24/7, with an average arrival of 45 minutes in 92037. See Is a Clogged Drain an Emergency? for how to decide.
Preventing the next one
- Bathrooms: fit hair catchers on every shower and tub, and clean them weekly.
- Kitchen: scrape plates and pans into the trash, and keep grease out of the sink.
- Toilets: only flush toilet paper. “Flushable” wipes aren’t, in practice.
- Laundry: fit a lint catcher on the washing machine’s drain hose.
- Condos: if your building has recurring stack backups, ask the HOA about scheduled stack jetting.
Frequently asked questions
Can I use a plunger on a drain with standing water?
Yes. Some standing water actually helps a cup plunger seal. Bail out most of it first so it doesn’t splash, and block any overflow opening.
Why does my sink fill with water from the other sink?
On a double kitchen sink, both bowls share one trap or drain line. If the shared line is clogged, water from one bowl comes up in the other. Block one side while you plunge the other.
How long should I wait before calling a plumber?
If plunging and cleaning the trap haven’t worked within half an hour or so, it’s time to call. Continuing to force a snake can damage old pipe.
Standing water that won’t go down? Call (858) 363-8328, or book online and save $49.