Washer Standpipe Height and Drain Hose Rules

The vertical pipe behind a washing machine looks like the least interesting part of a laundry room. It decides a lot, though. Too short and the washer siphons water out while it's trying to fill. Too tall and the drain pump strains to empty the tub. Too narrow and the spin drain overflows onto the floor. Manufacturers give minimums and maximums for that standpipe's height, plus rules for its diameter, its flow capacity and how far the drain hose goes in.

Whirlpool's figures

Whirlpool's front-load installation checklist tells owners to check that the top of the drain is at least 39 inches high, measured from the floor. It flags a drain hose pushed more than 4.5 inches into the pipe as a problem, and says to secure the hose without sealing it into the standpipe, leaving a gap for air.

Whirlpool's drain hose installation bulletin for its washers fills in the rest: a standpipe at least 2 inches in diameter, able to carry away at least 17 gallons per minute, with its top at least 39 inches high and no higher than 96 inches from the bottom of the washer. No more than 4.5 inches of hose should sit inside a floor standpipe, and if the drain has to be higher than 96 inches, the bulletin says a sump pump system is needed.

LG's figures

LG's spec sheet for its WT7150CW top-loader sets a different window. The end of the drain hose should be no lower than 29 inches and no higher than 96 inches above the bottom of the washer, and no more than 60 inches away from it, with a normal height of about 35 to 47 inches. The hose shouldn't go more than 8 inches into the standpipe, and LG warns against creating an airtight seal with tape. That sheet also says not to use the supplied drain hose with a floor drain.

LG's drain hose help page repeats the 96-inch maximum and adds two details: secure the hose with a tie strap and connect the elbow bracket within 4 inches of the end of the hose. Extra hose hanging past the bracket can let mold spread into the washer.

Making sense of the differences

The 96-inch ceiling is the same in both brands' documents. The minimums differ: Whirlpool asks for 39 inches, LG accepts 29. Hose depth differs too: Whirlpool's 4.5 inches versus LG's 8. Follow the guide for the washer you own. If you're not sure, a standpipe at 39 inches or more with a shallow, loose hose satisfies both.

The plumbing code that governs your standpipe measures its height a different way (above the trap weir rather than from the bottom of the washer) and sets its own limits, so a pipe that satisfies the appliance guide still needs to satisfy code. That's a plumber's call.

What each rule prevents

• •Minimum height. If the top of the standpipe is below the water level in the tub, water runs out by gravity while the washer fills. That's siphoning, and it wastes water and leaves the washer underfilled.
• •Maximum height. The drain pump can only lift so far. Above 96 inches it's working past what these guides allow.
• •Shallow, loose hose. A hose pushed deep or taped airtight can create a siphon. A loose fit lets air in and breaks it.
• •Diameter and flow. A modern washer pumps out water quickly. A narrow or partly clogged pipe can't keep up and overflows at the top.

DC laundry setups to watch

• •Basement laundry in rowhouses. Machines in English basements sometimes drain to a utility sink or a floor drain. LG's guidance against using its drain hose with a floor drain is worth knowing before you set a machine there.
• •Laundry closets upstairs. Renovations that moved laundry to a second-floor closet often used a recessed wall box with a short standpipe. Check that its height falls inside your washer's window.
• •Old cast-iron drains. Decades of lint and detergent residue can narrow an older drain line, reducing the flow it can carry. Overflows during the spin drain are the usual sign.
• •Flood-prone basements. If a basement takes water in heavy storms, a backup can come up through the floor drain and reach the washer before anything else. Our post on elevating appliances above flood level covers that side.

How to check your standpipe

1. Measure from the floor where the washer sits to the top of the standpipe. Compare with your washer's minimum and maximum.
2. Look inside the pipe. A standard 2-inch drain is about 2 inches across inside.
3. Pull the hose out and measure how much was in the pipe. Compare with your guide's limit.
4. Make sure the hose isn't taped or sealed into the opening.
5. Watch a full spin drain. Bubbling or water rising to the top of the pipe points to a capacity problem or a partial clog downstream.
6. If the washer drains into a utility sink, secure the hose over the edge with a strap so it can't fall in or jump out.

Symptoms of a standpipe problem

• •The washer keeps filling, or fills and drains at the same time.
• •Water spills over the standpipe during the spin.
• •Clothes come out wetter than usual because the pump is working against too much height.
• •A sewer or musty odor near the washer, sometimes from a hose that's pushed too deep.

A washer that drains perfectly can still shake if the floor under it flexes. See front-load washer floor requirements.

When to call a plumber

• •Raising, lowering or replacing a standpipe, or adding a trap, is plumbing work. The District's plumbing code governs those changes, and DC plumbing permits on the Department of Buildings Instant Permits page are issued only to licensed contractors.
• •A standpipe that overflows even with a correctly placed hose may have a clog or a venting problem in the drain line itself.
• •A sump or laundry pump system for a drain above 96 inches, or a basement setup, should be designed and installed by a plumber.

When to call us

If the standpipe meets your washer's specs and the machine still won't empty, drains slowly or shows a drain error, the problem is likely inside the washer: a clogged pump filter, a failing drain pump or a sock lodged in the hose. Our washer repair technicians can trace it from the tub to the standpipe.

Sources

• •Whirlpool: Front Load Washer Installation Checklist (39-inch minimum; 4.5-inch hose limit; don't seal)
• •Whirlpool: Drain hose installation bulletin W10608624 (2-inch, 17 gpm; 39 to 96 inches; sump pump above 96 inches)
• •LG: WT7150CW spec sheet (29 to 96 inches; 8-inch hose limit; no airtight seal; no floor drain)
• •LG: Top Load Washer - How to Install the Drain Hose (96-inch maximum; tie strap; elbow bracket within 4 inches)