One of the first things that you need to decide is whether you want to treat all the water coming out of the ground or just treat the water at particular places inside the house. If you want to treat all the water coming out of the ground you would install a whole house system and all the water entering into your house runs through that system but is not treated later (such as at a faucet or sink). If you decide to just work on individual parts of the house, you install a filter everywhere you want to remove contaminants. But this also creates additional problems. The filters that you install at every fixture do not necessarily treat each and every problem in the water. For example, shower filters are excellent at removing chlorine and softening the water. Some fixtures, such as a bathtub faucet do not have filters made for them. So point of use filtration is not a panacea.
The benefit of using point of use filtration is that it is cheaper than a whole house solution. However you cannot filter all the water, you have to change multiple filters, you cannot add chemicals, and you can only subtract contaminants. The benefit of the whole house solution is that you treat all the water at one spot, you only change one filter, and you can both remove contaminants and add chemicals as necessary. However, it is more expensive.More tips here
A well water filtration system is simply a fancy way of saying that we are going to filter and purify water that came out of a well rather than a municipal water supply. When water is processed through a municipal water supply system the water has many contaminants removed but the municipal water supplies also add chemicals such as chlorine as disinfectants. Because well water has not been processed by a municipal system, it still has the contaminants that would have been removed by the municipal system. However, it has not had the chemicals such as chlorine added to it either.
Treating well water means that we are going to remove impurities just as the municipal system did. It also means that we might add some chemicals, though different ones than the municipal folks would have added. If you have done a well water test recently you know both what needs to be removed and what needs to be added to make your well water pristine.