For example, I regularly plug a Micro USB cable into an iPhone charger and charge with that. Cheap, non phone chargers however, may not be regulated, and that could damage your phone. In short: Any cable or charger from an old phone is fine to use if its Micro USB (same connector).
Untreated surface water in rivers, streams, lakes, and ponds is not safe to drink unless it is treated to remove bacteria, viruses, and parasites.
Drinking water used for brushing teeth should be of safe water quality (e.g. boil water for one minute, bring water from a safe source, or buy bottled water). Showering with water that is bacterially unsafe (total coliform positive, E.coli negative) has a far lower risk of illness than drinking this water.