Plumbing: Waste Systems

Avoid Chemical Drain Cleaners

They are deadly to pipes, septic systems and pocketbooks

And away goes trouble down the drain!

Advertisements for liquid chemical drain cleaners are convincing. After all, backed up drains are a nightmare and not something anyone is well prepared for. Liquid drain cleaners make the prospect of clearing away any plumbing problems seem so neat and easy. Almost convenient. Just grab a can and pour it down the sink.

dangers of chemical drain cleaners
Chemical drain cleaner ad

But don’t believe it. Chemical drain cleaners are poisonous and dangerous to have laying around waiting for use. Once used, they end up in the sewer treatment plant and will eventually seep into the water system. They are also devastating to your plumbing and your septic tank if you have one. Here is a kitchen drain fitting that was destroyed by a liquid rooter chemical.

Dangers of chemical drain cleaners
Damage drain from chemical cleaners gone wrong!

Bad chemicals in the water supply

Do you know what chemicals are in that can of drain cleaner? And what happens when they get flushed into our water supply?

There are two basic types of drain cleaners, alkaline and acidic. Alkaline cleaners contain either sodium hydroxide or potassium hydroxide (lye). Acidic cleaners contain sulfuric acid in fairly strong concentrations.  Both of these can dissolve cellulose and proteins like hair, grease and fats.If you have a septic system, they will alsokill the good enzymes and bacteria in your septic tankthat help to break down the waste, so these cleaners should never be used if you are on a septic tank.


Lye, even in diluted amounts causes irritation of eyes with tearing, redness and swelling. Greater exposure causes severe burns and possible blindness if in the eyes. Chronic exposure and prolonged contact with diluted solutions or dust has a destructive effect on human tissue.

It is interesting that there is very little information available on the dangers of these chemical drain cleaners once they leach into the sewer system and water supply. Since drain cleaners are habitually washed down our drains, you would think the municipal systems would have a comment on it? Perhaps some reader will have some information and help me update this post.

Figure Out What’s Really Causing The Clog?

Think before you pour. Liquid drain cleaners only work on a few organic blockages. Yet, plumbing drains can run slow for many other reasons. Mechanical obstructions, improper slope and lack of plumbing vents can all cause problems with drainage.  

Instead of defaulting to the use of caustic chemicals, it is better to try to understand what might be causing the problem in the first place. Could something like a bottle cap have gotten into the drain? Perhaps there is a systemic problem with the plumbing itself? Is the plumbing in a difficult place that may have affected the slope of the piping. Maybe there is a lack of, or improper location of vents?

In the case of the photo below, the slow drain (that initiated the use of the chemical drain cleaner) was caused by inadequate slope to the plumbing and NOT by organic debris clogging the line. Not only was the liquid ineffective, since there was no slope, the chemical just sat in the line and eventually dissolved the pipe. Once the pipe was breached, the water leaked down into the ceiling and walls below causing water damage, mold and a repair bill in excess of $100K.

Image showing hole in drain pipe caused by chemical drain cleaner
Chemical drain cleaner damage to drain with no slope


Before using any chemical drain cleaner, try running a small plumbers snake or even a straightened coat hanger wire down the drain to see if that helps.


Also, you can act to prevent debris from entering the drains in the first place. Reduce the dumping of loads of garbage down your kitchen disposer and use removable screens over bathroom sink, tub and shower drains to reduce exposure to hair.



In the end, if you still have a persistent and stubbornly slow drain, have your plumber snake and video the line to troubleshoot the problem for a permanent repair. It may not be a blockage after all. In any case, avoid the chemicals. If drain cleaners can do this kind of damage to pipes, can you imagine what other unseen damage they might be causing downstream to sewer systems and water?

On the radio today Edwin Starr was asking “what is it good for” in his famous song about war.  I was pondering the exact question about drain cleaners and coming up with the same answer: “absolutely nothin’.”

dangers of chemical drain cleaners
Avoid liquid drain cleaners

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