A washing machine dumps its drum faster than almost anything else in the house. A laundry drain that is even slightly restricted will cope until it suddenly does not.
Laundry drains are deceptive. The pipe restricts gradually with lint and detergent residue, and for months nothing happens — because the only time it is genuinely tested is the few seconds when the machine empties its drum.
Then one day the standpipe cannot take it fast enough and you have water across the floor. Clearing the line and scouring the build-up off the pipe wall restores the capacity that was quietly disappearing.
Blocked drains rarely travel alone. Here is what else we handle.
Cleared properly, with the lint and detergent build-up actually removed.