How bad is it to soak rigid/hard contact lenses in solution meant for soft contact lenses?

I'm running a little low on the conditioning/soaking solution for my rigid/hard contact lenses and I'm currently in a third world country where the rigid conditioning/soaking solution seems nonexistent in markets, pharmacies, and optical stores--how bad would it be if I bought a container of the soft contact lens conditioning/soaking solution? Is there some other substance that would be better? (Water?)