How does a leak start?
October 26, 2019 2:56 PM   Subscribe

I woke up this morning to find water covering the floor in my bathroom, caused by a leak where the water supply line connects to the fill valve at the toilet. I’ve replaced the supply line and fill valve and the leak is resolved, but now I’m curious - how does a leak go from nonexistent one day to filling the floor of our bathroom, literally overnight? (I used the toilet at about 11:30 pm and again at about 7:30 am, so about 8 hours elapsed.) My prior experience with this kind of leak has been that they usually start very small; this wasn’t catastrophic but it wasn’t a little drip that got worse over time.
posted by devinemissk to Home & Garden (7 answers total) 2 users marked this as a favorite
Rapid unscheduled disassembly.

Similarly geologic events happen in spurts. The idea that mountains form slowly over a long time is a misconception. Geologic change happen in catastrophic events. Same with evolution.

What I'm saying, there's no rhyme or reason. The part was going to fail eventually. What the straw was that broke the camel's back is unpredictable.
posted by humboldt32 at 3:16 PM on October 26, 2019

What humboldt32 said but specifically in your case my best guess would be a rubber gasket failed after slowly deteriorating.
posted by The Deej at 3:56 PM on October 26, 2019 [1 favorite]

None of the pipes used in plumbing systems fit together in the snug waterproof way you would expect/hope. Hence the existence of teflon tape, rubber gaskets, or caulk at every connection.

Teflon tape, for example, has about the same tensile strength of a thick latex balloon. It's tough stuff, but how long do you think you could keep a balloon at house water pressure before it would spring a leak?

That isn't a precise analogy, I'm just trying to give a sense of the materials involved.
posted by Tell Me No Lies at 4:25 PM on October 26, 2019

Something like a change in temperature, or even air pressure, might be the straw that breaks the camel's back. Rubber (or often these days polyethylene) gaskets, or PTFE tape, or pipe joint compound all have a lifespan. Once a tiny leak starts, the pressure of the water enlarges the hole/gap, and things quickly get very leaky.
posted by pipeski at 4:55 PM on October 26, 2019 [2 favorites]

Small leaks that get incrementally bigger over a long time are generally associated with wear areas getting out of spec (hence a tap that starts dripping). But seals at non moving interfaces generally fail in a catastrophic way when environmental degradation takes their toll. They can be set off by a minor increase in condition limits like the small spike in pressure from closing a tap (flushing a toilet). And flowing pressurized water is fairly abrasive, once a leak starts things can escalate quickly.
posted by Mitheral at 5:09 PM on October 26, 2019 [5 favorites]

About a year ago I woke up one night to the sound of rushing water. The supply line to the toilet in my master bathroom had failed at the plastic nut connecting to the tank. Water was *gushing* against the walls at high pressure. It probably would have flooded half my house if it happened while I was at work. humboldt has the basic answer here - sometimes things work until they suddenly don’t.
posted by gnutron at 5:32 PM on October 26, 2019 [1 favorite]

Has it been raining quite a bit more than it was previously over the last week or two?

Lots of utilities will fill up reservoirs and water towers after a big rain in the watershed, and that raises the water pressure in a gravity-fed distribution system, sometimes very significantly.

Your house may or may not have a pressure limitation valve which should prevent your plumbing from experiencing that increase in pressure if there was one, but I lived in a house in Seattle where the cold water feed to the kitchen sink backed all the way out overnight a couple of days after a big storm ended a dry spell in the mountains, and I had noticed a big increase in water pressure when I was doing the dishes that night.

If you have a local plumbing supply store that the big boxes haven't put out of business yet, you could call and ask whether they've seen a big uptick in demand just recently.
posted by jamjam at 6:33 PM on October 26, 2019 [1 favorite]

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