ok, whats happening with the membranes. Is the TDS just rising and you 're thinking of replacing them? The ,membranes should last longer than a year. The weather is colder, thats not good for us producing water. Try flush out the membrane housings (with RO water). Maybe check your incoming tds, has that changed? Just being nosey but what is your incoming tds, and your product tds ? I suppose if its very high going in then your membrane life may be shortened a bit.