What's the proper way to throw out old shampoo or liquid beauty products?

Question

What's the proper way to throw out old shampoo or liquid beauty products?

Answer 1

Given that the substances are safe enough to be used on the human body with the possibility of getting into sensitive areas like the eye, it is safe to assume that most of these substances are soluble in water and will break down if doused with a large amount.  In other words, pour the stuff in the sink, turn the water on, and dilute it until there's nothing left.