Frogs do not "drink." They absorb the water they need through their skin. If their water is dirty or contaminated with chemicals they can become sick and even die. It is important that their water is kept clean.
One of the easiest ways to do this is to keep their water in a water dish. The water should be changed daily. Do not use soap or cleaners to clean the dish. Soak it in hot water if it is dirty and use a scrubbing pad that has no soap in it. Do not use bleach to clean the water dish.
Many cities treat their water with chemicals that are toxic to frogs (and fish). You should age the water by letting it stand overnight. This will not remove chloramines. You can buy water treatment chemicals at an aquarium shop. You can also use bottled "mountain spring" water. Do not use distilled water.
You can set up a tank with a large pond area that uses a filter, much like a fish tank. Even with a filter you have to constantly monitor the water quality. Frogs like to poop in their water and this can cause a build up of bacteria and make your frog sick.
One last note: If at all possible do not wash frog dishes in sinks used by people for food preparation or for bathing. Frogs can carry germs that make people sink. If you do have to use a bathtub or bathroom sink for washing, clean it afterward with a solution of bleach and water.
