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Drain Cleaner Debate

DEAR TIM: You're completely wrong in your past column about using Drano for clogs. If it doesn't unclog immediately, it stands in your drain and the acid erodes your pipes. At least, this is the case with older homes with galvanized iron and copper parts. I've got the bills to prove it. Dave Werner, New York, New York

DEAR DAVE: It might not be obvious at my website unless you go digging, but among other things I am a licensed master plumber. Over the years, I have developed a pretty good understanding of drain cleaners of all types. You are correct that some drain cleaners are acidic. Some are very dangerous acids that should only be used by professionals and even then with very great care.

Drano's active ingredient is sodium hypochlorite - chorline bleach.


Author's Note: At the time this original column was written, the previous statement was true. The latest information available from the manufacturer now states the formulation has been changed and the active ingredient is lye - sodium hydroxide.


It is not acidic by any means. It is actually a base and has a pH of 10 or greater. Yes, chlorine ions can be corrosive to certain metals if they are in *constant* contact with the metal over a *long* period of time.

If your theory is right, then I need you to prove it. I will assemble a metal drain p-trap of your choice made with any traditional plumbing metal you pick: galvanized iron, copper, cast iron or lead. Then, I will ship it to you and you prop it up and fill it to the brim with pure Drano. I guarantee you a dinner for four at the restaurant of your choice in NYC that the Drano will not eat a hole in the metal.

Your bills are from years of wear and tear on the drainage piping in your home. Drainage pipes actually do corrode and wear out over time. When a clog finally happens in an old pipe, the combination of drain cleaners and aggressive mechanical drain cleaning activities can easily poke a hole in a pipe. I have seen brass p-traps where the metal has become paper thin over time from normal wear and tear. Push a wooden toothpick into the bottom of the p-trap and presto you get a leak.

There is a natural way to keep your drains clean. It just takes a few minutes once a month as well as a couple of friends. Read my past column on this ingenious method that has worked for me for years.

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11 Responses to Drain Cleaner Debate

    • You can use it if you want because most older homes have metal drain lines. But Draino is a lightweight and no substitute for taking the trap off under a sink and inspecting the branch drain line to remove sludge and rust buildup. If the branch arm is galvanized pipe, you'll likely never open up the drain line.

  1. Hey Tim, glad I found this, thanks. Just replaced both 1.25" p traps connected to 1.25" galvanized pipes from two sinks to a t shaped pipe. That t drops 2 feet, turns 90 degrees then runs horizontal for about 12 feet to a 90 degree taking it 8.x feet below the slab. I know the clog is from the t to the horizontal because the washing machine isn't flooding lower on the same pipe.

    So far its been about an hour with Drano on both drains. Any predictions if the clog will clear before something bad happens? I will rinse all I can if it moves but I think I might have made a mistake doing this. I'm assuming the pipes are original 1957, new to me for 6 months.

    I'll let you know with pics if needed. I have before shots with timestamps.

    If it helps, when I filled one sink then let it drain, all kinds of rust and mineral looking stuff came up the other sink. I would guess that had something to do with ptraps, but plumbing is still magic to me. Couldmt day.

  2. Just an FYI..
    Pour hot water in drain to heat pipes before using products w/lye. Otherwise it can become a hard mass that may make things worse. js

  3. So is lye alright on the pipes?

    I used Hair & Grease (Instant Power) which says it uses lye. Bottle says it is safe on pipes. Plumber at the big box said it is safe on pipes.

    Overnight. 1972 copper piping.

    Plumber says the green stain on the drain pipe is a hole probably caused by drain cleaner and that it can eat a hole in only one use. I don't remember seeing that green stain last week and another plumber did not mention the hole last week. Used the lye cleaner the other night.

    I have used Hair & Grease before and Drano in the past but do not use them very often.

    • If you mix vinegar with baking soda you get an inert liquid. The two cancel each other out chemically.

      If you have a blockage, the only REAL WAY to clear it is to use a drain snake. The liquid drain cleaners only work for simple clogs.

  4. I believe it is the bubbling action of the vinegar and baking soda that can break up a clog.

    Why would they say the lye products are safe on pipes if they are very damaging.

    So would this mean it could have eaten or started holes all along the drain run until it reaches the stack. A lot of the piping is not visible. All of a sudden it will bust open to know?

    The hole he sees is on the top of the horizontal drain pipe which is between the overflow drain and the tub's drain hole.

    Thanks.

  5. I called the drain cleaner manufacturer. They said the lye is very weak (1% - 5%) and that their testing has shown it does not damage any type of pipe. They have been using it on the old metal pipes in their building for decades with no problem. Have been making it since 1968.

    Do not think my pipe has a hole. The green on it appears to be from where the gasket leak above it was dripping on the pipe.

    I don't like using chemicals so am going to use the enzyme/bacteria maintenance treatments. There is too much controversy over the potential for damage, anyway.

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