Five-minute kitchen leak check
Do this a few times a year and whenever an appliance is moved or replaced.
- Open the sink cabinet and feel the cabinet floor, especially the back corners, for softness or swelling
- Look for warped particleboard, lifted veneer or a water line on stored items
- Slide the refrigerator out and check the ice-maker supply line and its connection to the shutoff
- Shine a flashlight under the dishwasher through the toe kick to look for drips or staining
- Check the basement ceiling directly below the kitchen sink and dishwasher
- Smell inside the base cabinets with the doors closed for a while; mustiness is often the first clue
Why these leaks go unnoticed
Kitchen appliances connect with small supply lines and compression fittings that can loosen with vibration, age or a refrigerator pushed back too hard. Older thin plastic ice-maker tubing becomes brittle. Dishwasher drain hoses can crack where they loop under the sink. Each of these tends to leak slowly, a drip at a time, onto surfaces you never look at.
Cabinet boxes in many kitchens are particleboard or MDF, which swells and loses strength when wet and is a good food source for mold. Behind and under the cabinets, the subfloor may be plywood or older plank sheathing. In homes where the kitchen was remodeled but the basement below was finished separately, water can travel through the floor to a drywall ceiling, sometimes appearing several feet from the actual leak.
The kitchen scenario on many inspection reports is the same: the leak was found and fixed, but the cabinet base and subfloor were never dried, and growth followed weeks later.
What happens after a slow leak starts
Actual timing depends on the amount of water, the materials and the air around them.
- First days
- Water collects under the appliance or in the cabinet base; materials begin to absorb it.
- Within a day or two of staying wet
- Mold can begin to grow on wet, porous materials such as particleboard, drywall and paper backing.
- Weeks
- Cabinet bottoms swell, the subfloor darkens, and odor builds in closed cabinets.
- Months
- Growth can spread across the subfloor, into the wall behind the sink and onto the basement ceiling below; flooring above may cup or lift.
Questions once a leak is found
- Has a plumber confirmed the leak is fully repaired?
- How far did water travel under the cabinets and into the floor and wall?
- Can the cabinet be removed temporarily so the subfloor can be dried and inspected, rather than drilling holes and hoping?
- Does the basement ceiling below need to be opened to check the joists?
- Is this a sudden leak your homeowner's policy might treat differently from long-term seepage?
General information for Hilltop, not a quote or professional advice. In an emergency, call 911.