The Katadyn filters are very good too. You need to have a good Berkey or Katadyn filter because you just do not know what will happen in a large SHTF times. You may have to bug out because a large group is coming to your house and to save your family it is best to go than to fight a war that you may lose. Then you will need to find water that you may need to filter.
Always think of all things that may go wrong and prepare for them too.