How a Small Drip Ruined My Subfloor

Our kitchen faucet had a tiny, barely noticeable drip right at the base of the handle. It didn’t seem urgent; a quick wipe with a dish towel every evening kept the countertop dry. I figured I would get around to changing the internal O-ring over the weekend.

​I didn’t realize the water was finding a path of least resistance downward.

​While the countertop looked dry, water had been slowly seeping underneath the decorative chrome plate, running down the supply lines, and dripping directly into the dark cabinet below. Because the space was packed with cleaning supplies and paper towels, the moisture was absorbed before it could puddle out onto the kitchen floor.

​By the time I finally crawled under the sink with a wrench, the bottom of the vanity cabinet was completely black with rot and collapsed under the pressure of my hand. The water had even soaked through the subfloor below, ruining the plaster on the basement ceiling directly underneath the kitchen.

​What should have been a $5 O-ring replacement turned into a full-scale demolition of the sink base, replacing a section of the kitchen subfloor, and patching drywall downstairs. If you see water anywhere it shouldn’t be, don’t wait find out exactly where it’s traveling before it finds a way to ruin your house.

Richard, sorry this one sat for a few weeks. It’s a better warning than most prevention articles, because this is exactly how it happens. Fast leaks announce themselves. A slow drip at the base of a handle just follows the supply line down into the cabinet, and the stuff stored under there soaks it up before a puddle ever makes it out where you’d see it. We’ve opened up kitchens after this same story: cabinet floor black and soft, countertop above bone dry.

Two cheap habits catch most of these. Empty the under-sink cabinet once a season and run your hand along the supply lines and shutoff valves. Fingers find dampness that eyes miss. A leak alarm puck under the sink helps too, about $15 at any hardware store.

How far did it go in the end? Did the subfloor come out back to the joists, or was it salvageable once it dried? And was the O-ring swap the five minute job it should have been once you got the wrench on it? Curious how it ended.