Chemical drain cleaner

20 Sep 2020
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United Kingdom
Hi folks, wondering whether an off-the-shelf liquid drain cleaner can damage pvc waste pipes if left for too long (like weeks or months). I’ve just locked up my holiday house for the season but before I left, I poured a little liquid drain cleaner down each plug hole (showers and sinks). I didn’t rinse it through but thought I’d leave the stuff to seep thru any gunk until the next time I go back - give it a nice long time. Now I’m fretting that this may have been a daft thing to do. I thought these shop-bought liquid drain cleaners were fairly harmless to waste pipes but now I’m wondering. Unfortunately, I can’t remember the brand I used. I didn’t use massive amounts - one bottle between three shower wastes and three sink wastes. Thanks in anticipation.
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Pretty sure that stuff should be okay if you bought it from, say, a supermarket. A mate of mine used some heavy duty drain cleaner once that he bought from a builders merchants years ago to clean his bath waste out and left it in overnight. The waste pipe sagged between the joists and he had to replace the lot.
Dangerous stuff. I had a mate who had a waste trap disintegrate on him and he had pretty severe burns from the cleaner.
The super strong stuff you can get from plumbers merchants is a concentrated acid. It's only supposed to be sold to tradespeople, I think strictly just to plumbers.

It reacts with water, and produces heat. If you add too much, too quickly, it can produce enough heat to melt the pipes, which could be what happened in these two cases.

EDIT: It's also extremely caustic, and will cause very severe burns to skin.
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The off-the-shelf stuff you get from a DIY store is pretty innocuous and should be fine to be left in. The proper trade stuff needs careful handling
Is it an actual house? Just thinking if you’re bothered that much is there anyone who can go in and flush it out? Perhaps next time use soda crystals and boiling hot water, or maybe just rinse afterwards?

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