As fans of good-tasting and especially of clean water, we've used a pitcher water filter for some time. I know it's time to change the filter when I figure out I'm not drinking water because it tastes bad even after filtering.
After doing some math, we discovered that in the long run, it's actually cheaper (not to mention healthier) to have one of the big-daddy under-sink filters where all you have to do is turn on a faucet and voila! Clean, delicious water! I ordered one from a trusted company and waited patiently. Well... sort of patiently.