The short answer
When a washing machine drain backs up in a Northern Virginia house, where the water comes out tells you where the clog is. Out the top of the standpipe behind the washer means lint in that pipe or its trap. In the laundry sink means the sink’s own drain. In a basement floor drain, a shower or a gurgling toilet means the main line or a line the washer shares. Washers push water out faster than any sink, so they find a partial clog before anything else in the house does.
Why the washer finds the clog first
A washer’s pump empties a full tub of water in a couple of minutes. A sink or a shower trickles by comparison. A drain line that’s half closed with lint or roots still keeps up with a sink, so nothing seems wrong, until the washer dumps its load and the water has nowhere to go but back up and out the lowest opening it can find.
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Where the water comes out
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| Where the water shows up | The clog is probably | What to do first |
|---|---|---|
| Out the top of the standpipe behind the washer | In the standpipe, its trap or the line right after | Check the hose, then snake the standpipe |
| In the laundry sink the washer drains into | The laundry sink’s own drain | Pull the lint out of the sink drain, add a lint catcher |
| In a basement floor drain | Past where the laundry ties in, often the main line | Stop the washer (floor drain backing up) |
| In a shower or tub, or a toilet gurgles | The main line or a shared branch | Stop running water and call |
The standpipe behind the washer
The standpipe is the open pipe the washer hose hooks into, with a trap at the bottom of it inside the wall. Three things back it up:
- Lint. Most of the lint in a wash leaves with the water, not in the dryer’s lint screen. Towels, fleece and pet hair shed the most. It settles in the trap and builds up.
- A small drain. Newer houses get a two-inch laundry drain. Older ones often have an inch-and-a-half drain that a modern washer can outrun even when it’s clean.
- The hose pushed too far in. The hose should hang a few inches into the standpipe, loose. Jammed down to the trap, it can seal off the air the drain needs or siphon water back into the washer.
A quarter-inch hand snake down the standpipe clears most lint clogs. How to use a drain snake walks through it. Don’t pour chemical drain cleaner into a standpipe. It sits in the trap and comes back up with the next load, and it is hard on older pipes anyway.
The laundry sink
In a lot of basements the washer hose drains into a laundry sink. Those sink drains are small and catch lint fast. Pull out what you can reach, plunge it, and put a mesh lint catcher on the end of the washer hose. They’re cheap, they catch a surprising amount, and you swap them out when they fill.
Floor drain, shower or toilet: the main line
Water coming up somewhere other than the laundry is the one to take seriously. The washer’s water went down fine and hit a clog further along, and the next opening down the line is where it came out. That’s usually the main line out to the street: roots, grease, or a sag that collects lint. Stop running the washer and every other drain until it’s cleared, because each load goes straight to the floor. Main sewer line clog covers the signs and one drain or the main line helps you tell which you have.
A main line that backs up when the washer runs can often be cleared the same day from the cleanout. If it keeps coming back, a camera shows why.
When the laundry is upstairs
A lot of newer Northern Virginia houses have the laundry on the second floor. A backed-up standpipe there doesn’t puddle in the basement. It soaks the floor under the washer and shows up as a stain on the ceiling in the room under it. A drain pan under the washer with its own drain line catches the small ones. If you see a ceiling stain under the laundry, turn the washer off and get the drain looked at before the next load.
Keep it from coming back
- A lint catcher on the hose if it drains into a sink. Swap it when it fills.
- Use the amount of detergent the washer calls for. Too much makes suds that can push up out of the standpipe.
- Liquid detergent dissolves better than powder in cold washes.
- If the standpipe overflows on every big load, the drain may simply be too small for the washer. A plumber can tell you.
A washer drain that backs up is one of your house’s warning lights, and it’s usually telling you about the line, not the washer. Error codes and warning lights at home covers the rest of them.
When you’d rather we do it
A sink clogged at the trap is $99 with our sink clearing offer, up to the P-trap. A toilet, tub, shower or any drain past the trap is drain cleaning, $200 to $800. The main line to the street runs $550 to $1,650, and when grease or roots keep coming back, hydro jetting clears the pipe wall. You get the price before we start. A plumbing diagnosis visit is $49, or $250 after hours.
Call (703) 997-9757, day or night, or see every current deal on our offers page. Rated 5.0 stars across 1,138 reviews on Google, Angi, Yelp, the BBB and Facebook, Virginia Class A license 2705192276.
Questions people ask
Why is my washing machine drain backing up?
Usually lint in the standpipe or its trap. If the water comes up somewhere else, like a floor drain or a shower, the clog is in the main line or a shared drain line.
Why does my floor drain back up when the washing machine drains?
The washer’s water hits a clog past where the laundry ties in, often in the main line, and comes up at the lowest opening, which is the floor drain.
Why does water come up in my shower when the washer drains?
The shower and the washer share a drain line and the clog is past where they meet. Stop using water and have the line cleared.
Can I use drain cleaner in a washing machine standpipe?
It’s better not to. It sits in the trap, comes back up with the next load, and it’s hard on older pipe. A small hand snake works better.
How do I stop lint from clogging my washer drain?
A mesh lint catcher on the end of the washer hose catches most of it if the hose drains into a sink. Towels and fleece shed the most lint.
