View Full Version : Is It OK (For My Pipes In The Crawl Space) If I Disinfect The Crawl Space With Bleach

08-12-2012, 11:38 AM
Hi Everyone,

First time poster, long time lurker.

I have a 9 unit apartment building and there are some feral cats living underneath the crawlspace. I found a licensed company to remove the cats with permits from the city and I also wanted to have the crawlspace cleaned by the same company.

The company said they can "disinfect" the crawlspaces and when I asked what that entailed, he said that they spray the crawl space with bleach.

My questions is if this a good idea? Does it effect the pipes in any way? I re-piped the building with copper pipes a decade ago and don't want to damage or corrode anything.

Thank you in advance,


08-12-2012, 01:45 PM
Bleach WILL corrode copper piping.

If I were you, I'd just get rid of the cats and scrape the cat poop into buckets and dump those buckets onto a grassed area and let Mother Nature take care of the stuff.

08-12-2012, 04:19 PM
You could always spray off the bleach a day later with water. Let the whole thing dry out afterwards and be in good shape. Yeah, bleach will corrode copper, but so will many things. Even deionized water corrodes copper. Time and concentration are the driving issues.

08-12-2012, 08:25 PM
Using an ozone generator or spraying hydrogen peroxide will do the same thing as bleach without spraying chlorine all over your copper pipes. It's the chlorine in the bleach that reacts with copper to form a blueish green compound commonly called "verdigris".


Bleach (NaOCl), ozone (O3), and hydrogen peroxide (HOOH) are all "oxidizing bleaches" because they all work exactly the same way. They all spontaneously break down to form more stable compounds, and release a lone oxygen atom in the process of breaking down.

Ozone (O3) spontaneously breaks down to form an oxygen molecule (O2) and spits out a lone oxygen atom when it does that. Hydrogen peroxide (HOOH) spontaneously breaks down to form water (H2O) and releases an oxygen atom. And, and a gallon of Chlorox bleach will gradually transform itself into a gallon of Chlorox salt water and a whole mess of oxygen atoms given time.

It's those lone oxygen atoms that remove the colour from your t-shirt or remove the smell from the air. See the section below that you don't need to know to find out how they do that.

So, an ozone generator would sterilize your crawl space just as effectively as spraying bleach all over the place without actually spraying any bleach, and thereby avoiding harm to your copper piping.

Alternatively, spray hydrogen peroxide in your crawl space several times instead of one spraying of bleach. Hydrogen peroxide breaks down much more slowly, and therefore isn't as harsh to handle or have as strong a sterilizing effect as bleach. Also, you can typically only buy hydrogen peroxide in a 3 percent concentration, which is only about half the concentration of NaOCl in bleach.

If you look under "Janitorial Equipment & Supplies" in your yellow pages phone directory, many of the companies listed there will rent ozone generators, also called "ozone machines". If they don't, they'll probably know who does. Ozone isn't healthy to breathe, so it's best to turn the ozone generator on, get out of that crawl space and then plug in the long extension cord to the generator. Similarily, after a day or so, unplug the ozone generator and wait a few hours for the ozone in the crawl space to break down into oxygen molecules before retrieving the ozone generator.

Ozone machines come in different sizes and the people at the janitorial supply store can help determine what size you need based on the size of your crawl space and how long you're wanting to rent it for.

(Post again if you want to know why ozone, oxygen molecules or oxygen atoms shouldn't harm your copper piping.)

You don't need to know the rest...

Now, how to put this politely?

Lone oxygen atoms are the horny drunken sailors of the chemical world. They'll react with anything that's unstable enough to react with them, and that typically means stuff that decomposes on it's own in time, and for the most part, that means large organic molecules.

The way oxidizing bleaches work is that when oxygen atoms react with a large organic molecule, they break that large molecule into pieces, and those pieces don't absorb the same wavelengths of light or affect the olefactory sensors in our noses (or undoubtedly the taste buds on our tongues) the same way as the original molecule did. So, the dye that made a t-shirt red is still on the shirt after bleaching it, but those red dye molecules are in pieces, and those pieces don't absorb the wavelengths of light the original dye molecules did to produce the red colour we saw. So, what we see is the cotton without the effect of the dye on it, or white cotton.

But, those oxygen atoms don't know that we only want them to attack certain large organic molecules (the ones that are causing a stain or causing a smell), so they'll react with any and every large organic molecule they come into contact with.

For example, cellulose, like starch, is nothing more than sugar molecules stacked up like bricks in a wall. Cellulose is a large organic molecule. Wood is mostly made out of cellulose and cotton is nearly 100% cellulose. If you leave a cellulose sponge soaking in bleach over night, what you'll have in the morning will still look like the same sponge, but it'll tear into pieces very easily because so many of the cellulose molecules in it are broken to pieces that the sponge no longer has any strength. Ditto for soaking cotton in bleach.

Oxygen atoms "sterilize" by reacting with the large organic molecules that bacteria and "germs" are made of. Nothing can survive having the molecules it's made of being broken into pieces.

By using an ozone machine instead of bleach, you get the same lone oxygen atoms produced that bleach will provide, and therefore the same sterilizing effect, but you DON'T have any chlorine present, which is what reacts with the copper to form copper chloride (also called "vertigris").

PS: An ozone machine is the biggest gun in the arsenal when it comes to removing smells. When someone who lives alone dies in their house and the body isn't discovered until the neighbors start to complain about the awful smell coming from the house, it's an ozone machine (or several of them) that's used to remove the smell from the house after the body is relocated.

08-12-2012, 11:43 PM
So basically, an ozone machine is the only form of sterilizing method that won't damage my investment in copper pipping? If I put one (or more) machines in the crawl space, could the ozone rise up and harm my tenants? I don't want to harm anyone's health. I would obviously need to make sure the city of Los Angeles allows them too. I like to follow things by the book.

Thanks for your insights though! Any additional thoughts are welcome.

08-13-2012, 10:05 AM
So basically, an ozone machine is the only form of sterilizing method that won't damage my investment in copper pipping?

No, you could hire some high school students to gather up that cat poop with lawn rakes, scoop it into buckets and dispose of that stuff on the grassed area around your building (if you have such a yard) so that the poop will decompose and nourish the soil.

You could also spray multiple times over a longer time frame with hydrogen peroxide, which won't harm your pipes either.

You just need those lone oxygen atoms to destroy the bacteria growing on the cat poop, but you want to avoid using chlorine because it'll react with the copper of your piping. And, both ozone and hydrogen peroxide will provide oxygen atoms without the presence of chlorine.

Ozone breaks down to form oxygen atoms the most rapidly, so it's the most aggressive when it comes to sterilizing. Hydrogen peroxide breaks down to form oxygen atoms the most slowly, so it's the kindest gentlest oxidizing bleach.

If it wuz me, I'd hire high school kids to do your dirty work and let Mother Nature put that cat poop to productive use. If they didn't want the job, I'd use the ozone generator.

You don't need to know the rest...
One of the reasons that hydrogen peroxide is only available to the general public in a mere 3 percent concentration is related to the reason why a few years ago the FAA decided passengers weren't allowed to carry liquids onto passenger airplanes in their carry-on bags. And, if you start inquiring about buying pure hydrogen peroxide, you're likely to attract the interest of your Department of Homeland Security. That reason is that acetone and concentrated hydrogen peroxide are the two ingredients needed to make a high explosive called "acetone peroxide". Apparantly, your CIA got information that Al Qaida was planning to have two martyrs take pure hydrogen peroxide and acetone onto an commercial airliner separately, and make acetone peroxide during the flight. Neither component would be considered dangerous on it's own, but when mixed together and properly prepared would produce a white powder that's considered a "high" explosive that could easily knock a plane out of the air. So, the FAA barred passengers from taking any liquids onto the flights on their persons or in their carry-on bags for fear of another terrorist attack.