There are no dumb questions, particularly when it comes to water treatment. How you treat your water ultimately depends on your supply. Here in New York there has been a statewide increase in the amount of chlorine added to tap water. My local water supply is also notorious for contaminants. Therefore, I use a reverse osmosis system for all my frogs vivarium water and I use distilled water for my misting systems. The goal is ultimately to provide water as free from contaminants as possible. Also, purified water leaves terrarium glass much cleaner as there are no mineral deposits. Note, I only use distilled in my misting systems as any minerals will quickly wear out and clog the nozzles. There are recommendations that distilled water not be used for water dishes and water features exclusively as it eliminates too many minerals. However there are mineral additives available at aquarium suppliers if you chose this method. If you have only a single frog you could probably just use quality bottled water.