Drano then Sulfuric Acid

Our house has sat empty for months. Yesterday we returned to get some things. I ran the kitchen sink, and it wouldn’t drain. I plunged it. Nothing. I poured a half-bottle of Drano Professional or Max or whatever down it. Nothing. I carefully plunged again. Nothing. I poured a few ounces of Marc 55 Drain Cleaner (viz., Sulfuric acid) next. It bubbled some and stank (the room was ventilated), boiled up some nastiness from the depths, but the clog remains.

I see now that I dumped a highly caustic acid on top of a base, hence the bubbling, smell, etc. We’re going back today with a drain snake, gloves, and goggles. There’s maybe 12 oz. of Sulfuric acid and 16 or so oz. of Drano in the pipes. Is there any special danger involved? After 18 hours, has whatever was gonna happen, happened?

IANAP but I’m guessing you might have seriously weakened the pipes. But the major damage would have happened in the first 10 minutes. Another 18 hours probably didn’t make it much worse. There’s a decent chance that the snake will poke though the walls of one of your pipes. Be careful not to get the stuff on you. Wear gloves and eye protection.

Yes, there is a danger of damaging metal drain pipes. I had a bathroom sink that drained slowly so I used a standard drain cleaner. Because the house had settled the main drain line no longer had a slope to it so the acid just sat there until it ate a 2" x 8" hole in the pipe. I discovered this after taking a shower and all the water went into the room below.

I don’t know if PVC suffers the same fate and I have no intentions of finding out after replacing every bit of line and installing a new ceiling.

So, if it were me, I’d get the drain cleared out and flushed sooner than later. The reason you can’t plunge it is you might have a vent between you and the clog and all you’re doing is pumping air up and down the vent.

hold the horses with respect to mixing the two substances - doesn’t high school chemistry teach us the acid and base (caustic soda aka lye aka drain cleaner) will effectively be neutralizing each other, with potentially toxic (but probably inert salts) as byproducts? Also heat etc - hence the bubbling nastiness.

I’d personally be surprised if you damaged the pipes permanently, assuming the quantities are roughly even and you followed the directions on the packet. You did flush the hell out of it with water after you finished? Even if not, just duck back there and flush away with water.

My advice would be to next try just plain old boiling water, in quantity. Like not a kettle - boil up a big pot and work out a way to safely put it down the pipes. In my experience (and my plumber friends advice) this is far more effective than chemical and better for the environment.

YMMV depending on construction material of the pipes, but any sort of HDPE, PVC, copper or steel will be able to shrug off ~90deg C water.

Missed edit window - but thought i should add - on the boiling water, I’m actually not sure if your local area building method uses glued joints or other design features that may be sensitive to boiling water, so maybe consider that before trying it. I’m basing it on my local building experience that boiling water can’t damage the pipes as built here. Might be different where you are at.

If you haven’t done this already put a bucket underneath the trap with some water in it to dilute any chemicals and pull the P trap out. Chase the clog with a snake from that point forward. Wear gloves and goggles so you don’t splash anything in your eyes.

I don’t know about glued joints (never had an issue*), but I can tell you that you shouldn’t pour boiling water down a disposal. It WILL melt some internal parts and eventually ruin it. I’ve seen it happen more than once.

*Personally, I make a habit of always running cold water when dumping boiling water down the drain, sort of a ‘why risk it’ thing. I never dump boiling water down the disposal to begin with, but still, might as well cool the water and not risk damaging the pipes (that I don’t think can be damaged to begin with.

It is dangerous to ever put any chemicals down a drain. Only use chemicals in drains that you are going to walk away from.

You now have dangerous chemicals in your drain pipes. And they will be a danger to anyone working on said drain. Suit up take the P trap apart. put it in a safety container and depose. If the plug was in the P trap put a new on and flush drain with plenty of water. If the plug is past the P trap continue with extreme caution.

DO NOT ASSUME THE TWO CHEMICALS HAVE NEUTRALIZED EACH OTHER. You would have to mix in proper volumes to reach a neutral state and the salts are going to be harmful.

When I was working if I went to a new building and there was any chemical drain cleaners near the shop, I went through the problem of getting ride of a hazardous waste.