Bleach in drain cleaners I have a clogged pipe in my bathroom so I went to the store to get something to unclog it. Basically there are two types that you can find in my area:


Sodium hydroxide pellets
"Liquid plumber" mixtures. The components for those are mainly surfactants, sodium hydroxide and sodium hypochlorite.


As far as I recall from the water treatment courses I took in college, hypochlorite's oxidizing activity is heavily dependent on pH, as the active form is hypochlorous acid, not the hypochlorite ion. At high pH values the oxidizing activity becomes really low whereas low pH will make it stronger.

Does it make sense to buy a product that mixes a strong base, such as sodium hydroxide, with sodium hypochlorite? Wouldn't it be a waste of money?
Lye is very corrosive, just like acid, except opposite (hope that makes sense). Although lye is a very powerful chemical, and it is sufficient for many blockages, oxidizing agents (like bleach) may be helpful for breaking down paper/cellulose blockages.

Mixing bleach with acid will cause chlorine gas evolution... bad, bad, bad.

EDIT- The oxidative powers of hypochlorous acid and hypochlorite ion(s) compared:



Source: Descriptive Inorganic Chemistry, Third Edition (By Geoff Rayner-Canham, Tina Overton)

So in terms of power, yes hypochlorous acid is a stronger oxidizer, but it's not wildly different. 

On a related note (see comments below) hypochlorous acid is a much better microbicide than the hypochlorite ion, because it penetrates cell walls more easily. However, regarding a drain cleaner, the oxidative difference is much less pronounced. And it's worth mentioning that at above pH 12, a cell will lyse (burst open) and become saponified, so that obviates whatever microbial effect hypochlorite or hypochlorous acid might have on bacteria... like being thrown into a poisonous wood chipper.