Posted By Cr8r Jenny I thought most drain unblockers were based on caustic soda (sodium hydroxide). Don't get me wrong, this is still nasty stuff (has to be to do the job - dissolving fats, hair etc), however it doesn't react with water, so would appear from what you say to be a little better than sulphuric acid. This isn't my field though, so perhaps an expert will offer further advice.

Posted By Charley Farley-Trelawney This is a tricky one, it is generally around 93% Sulphuric Acid and one of its first jobs was external 'soak aways' to melt (so to speak) leaves and the like so gutters could flow. It is highly dangerous used in the incorrect manner and there are many restrictions concerning its use, i.e. storage, skin/eye contact, who is trained to use it, respiratory, correct SDS's, etc etc etc, I would look to find a more suitable product or find another way to unblock (jetting etc) it must never ever be mixed with anything else, residue of previous chemicals can be a serious problem, the gas is not nice, trust me, I know. Elimination of the product has to be the number 1 priority (all in my humble opinion) Charles