A:Answer I'm a money-miser, so I'm with you, pushing the limits of water filters and anything else I can stretch to their max. Technically, I see that the ability for your filter to capture impurities will be greater if you have a better source. Certainly, though, the properties of your filter will begin to break down themselves over time and allow some of those impurities to pass through. So, try not go go too much further than recommended replacement date by 4-8 weeks and you should be fine. Things I would look for are changes in the flow rate and/or changes in taste (though these may be subtle).
