As I understand it, the radioactivity of a particle is independent of the chemical property: that is, the same chemical reactions work in the same way on radioactive particles as they do on their non-radioactive counterparts.

Thus, to precipitate particles out of water, you need a chemical reaction that is probably unique to that chemical element or molecule. Since a large variety of elemental particles/molecules can become radioactive, I am going to guess that it is unlikely that their is a single, or even a small number of chemical reactions that would precipitate out every possible radioactive element.

This exhausts my physics and chemistry.

Blast---can you give us some input from someone who actually knows what he is talking about?