The scales that claim to calculate body fat - or bmi - don't really do an accurate job. It just uses a mathematical calculation that doesn't take into account your real body composition -- if you've got a lot of muscle mass, it's going to count it as weight in that equation. Hope I'm making sense.
I never heard of a scale that measures water-- again, how can a scale "know" what your physical makeup is?
I have a cheap Weight Watcher's brand digital scale that I got at Walmart several years ago. Never needed to replace the batteries, and I like that it measures in half-pound increments. Oh, and I can read the numbers without my glasses!
Good luck with your search - hope you find something you'll be happy with!
~>New Year's Day Challenge: 220 on 1/1/2012<~
*** Goal #1 - Healthy BMI***I want to stop finding the weight I've already lost