Slow Kitchen Leak in Cromer: Traced to Plumbing Tape on a Dishwasher Connection

The situation

A homeowner in Cromer had a leak under the kitchen sink that would not go away. The husband and a friend had already had a go at fixing it themselves. Before us, another plumber had also looked at it. It was still leaking.

The drip itself was small, easy to dismiss as not worth the fuss. But it had been running long enough to swell and stain the cabinet base underneath the sink, and to get under the floor tiles nearby, which had started to pop up over time. A single slow drip, one every so often, adds up to a full bucket of water finding its way into cabinetry and subfloor over a day or two. That’s the part people underestimate about a “small” leak.

What we found

With two prior attempts already having missed it, the fault wasn’t going to be obvious. We went through the wet area joint by joint rather than assuming the leak was where it looked like it was pooling, since water travels before it shows itself.

That inspection led to the dishwasher’s water connection. Someone, at some point, had wrapped it in plumbing tape (the thread seal tape used on threaded metal joints). The problem is that a dishwasher connection isn’t a threaded joint that relies on tape. It seals with a rubber washer built into the fitting. Adding tape on top of that does two things, both bad:

• It stops the connection tightening down properly, because the tape adds bulk where the fitting needs to seat flush.
• It gets pressed into the rubber seal itself, leaving a permanent imperfection on the face that’s supposed to seal the water. Once that rubber is marked, it leaks regardless of how tight the fitting is.

That’s a fault that’s easy to create and easy to miss if you don’t already know a dishwasher connection isn’t meant to be taped, which is likely how it slipped past an earlier repair attempt.

The fix

The repair was straightforward once the actual fault was identified: take the connection apart, remove the plumbing tape that had no business being there, and reinstall it relying on the rubber seal alone as it was designed to.

Tightening it back up is its own skill. Firm enough to seal properly, but not so tight that you distort or shift the rubber to one side, which can create a new leak path from the opposite direction. Firm but not overtight is the target, and knowing where that line sits for a given fitting comes down to experience rather than a torque spec.

A slow leak isn’t a small problem, it’s a problem you haven’t seen the size of yet. One drop every so often can still fill a bucket in a day.

The outcome

The leak was resolved in the one visit, with no new parts required, just correcting a seal that had been compromised by tape it never needed. The homeowner now has a dry cabinet and no ongoing damage to the tiles.

It’s a fault that had already survived a DIY attempt and a professional visit, which is really a reminder that diagnosing a slow leak is about experience and attention to detail, not just tools. Knowing which joints in a kitchen do and don’t need thread tape, and being willing to check every joint above the wet area rather than the obvious one, is what finds a fault like this. Fixed the day it was called in, it’s damage that could have been avoided months earlier.

Slow drip under your sink that won’t quit? Our leak repairs team inspects every joint in the wet area, not just the one that looks suspicious, and covers Cromer and the rest of the Northern Beaches. If it’s a tap rather than an appliance connection, see our leaking tap repairs page.