Washing machine and appliance overflows
The rubber supply hoses behind a washing machine are under full house pressure every hour of every day, whether the machine is running or not. They are the most common single point of failure in a laundry room.
- 1 The ceiling stain. The wet spot is the end of the path, not the start of it.
- 2 A burst supply line. Under pressure, so it does not wait for anyone to notice.
- 3 A frozen line. The run inside an exterior wall is the one that gives in January.
- 4 The washer hose. Braided or rubber, behind a machine nobody moves for years at a time.
- 5 The water heater. The tank opens at a seam, and it opens without warning.
- 6 Groundwater and backup. A high table pushing at the footing, and a drain that runs backwards in a heavy week.
Hoses fail while nobody is home
A burst hose releases at line pressure until someone closes the valve. The standard advice: replace rubber hoses with braided stainless every five years, and close the valves when leaving for more than a few days, is unglamorous and it costs less than almost anything else a homeowner can do.
The standpipe backup
A washing machine pumps out faster than a partially blocked standpipe can drain. Water comes back up and over, usually onto a basement floor, usually during a wash cycle nobody is watching. Lint, detergent residue and, in older houses, a partly obstructed lateral are the usual causes.
The slow ones are the expensive ones
A dishwasher seeping under a cabinet base, a refrigerator ice-maker line weeping behind the unit, a laundry connection dripping into a wall cavity, none of these announce themselves. They are found by smell, by a soft floor, or by a stain appearing on a ceiling below.
What a leak alarm can and cannot do
There are two categories of device sold for this and they are not close to equivalent. A battery puck sitting on the floor sounds when its contacts get wet, which is worth having and helps only if somebody is home to hear it. The other kind is plumbed in: a sensor wired to a motorized valve that closes the supply on its own, with no one in the house and no one to call. For the failure this page is about, a hose letting go at line pressure while the family is at work, only the second category changes the outcome.
Neither one substitutes for closing the two valves behind the machine before a week away, which remains the move that costs nothing. And it is worth knowing that some New Jersey insurers will look more kindly on a home with an automatic shut-off installed; whether that is true of yours is a question for your own policy rather than something to assume.