agreed. the piece of mind doesn't cost much. I like the fact my TDS meter reads 0 tds
Oh if you get a RO/DI system, add on a tds meter. if I didn't have my TDS meter I wouldn't have known my RO/DI wasn't set up properly the first time. Very good thing to have. handheld ones are fine since I only need to check it every 6 months anyways.