There are many treatment methods. Common methods are as simple as a catlytic GAC or a KDF 85 backwashing filter, to chlorine injection / contact tank / GAC, or manganese dioxide ore media backwashing systems, simple aeration, etc. Each method has its advantages and disadvantages and each person who does water treatment will have their preferred method. I lean toward the manganese dioxide based medias mainly because they work almost every time, are extremely simple, and they also clarify the water, remove iron, and manganese. They have a disadvantage in that they need excessive backwash flow rates, and are slightly expensive. KDF85 also works very similarly to Mag Ox medias, but is even more expensive. Catalytic carbon works fairly well, it works great when combined with an oxidizing agent and a contact tank. What other water issues are there? What kind of equipment is alrewady installed? Do they have an atmospheric storage tank? Many factors will come into play to determine the "best" treatment method.
Hope this helps,