We were using Aqua guard we felt that taste of purified water was bad & had stomach ache sometime, we thought to change new purifier, one of my relative is using Puritee Hot from past 2+ years & the have shared good feedback about their water quality & services, we bought X7 using it from past 6+ months, great taste & good service. We had recent filter replacement service, was done very quickly, I endorse their product & service, just go for it. I saw some negative comments here in site, no sure how those can be but looks like AO Smith has resolved them.