Randi - I only change the water every few days for my crew of five unless I see debris in the water - it seems to stay very fresh! Every few days I dump everything and spray it out with the sink hose. I take it apart at least once a month and scrub everything and start fresh. I also change filters when they start looking dingy which is usually every three months or so. I have had mine about two years?? now and even though I scrub it. there are mineral deposits on it here and is starting to look dingy even though I know it is very clean.