Are you sure you have an NR71? or is it an NRC model? only NRC models should be getting that code. Anyways, your house water treatment system has nothing to do with the neutralizer. The Neutralizer that it is telling you to replace is not there to treat the water going to your house. It is neutralizing the acidic condensate produced by the exhaust in your "condensing" unit. Without a new Neutralizer the condensate that drains out the bottom of the unit will be strong enough to kill plants and eat away very slowly at some items or metals underneath the skinny condensate drain. It's not a big deal unless you have the unit sitting above something you really care about and there's no condensate drain pipe attached. Either way, if you buy a new Neutralizer it comes with instructions on how to reset the timer so that you don't have to have the EC 92 bug you anymore.