First, test your tap water before you buy. That $10 test kit from Amazon can save you from buying a $500 hammer for a fly. If your main complaint is taste, a $30 charcoal filter might be enough. If you have lead or arsenic, RO is your hero.
Second, measure your under-sink space. Many systems are the size of a small cat. You don’t want to end up storing cleaning supplies on your counter because the tank won’t fit. Measure twice, buy once—like carpentry, plumbing, and life.
Third, look for certifications. NSF/ANSI Standard 58 is the gold standard for RO. If the box doesn’t mention it, you’re buying a pretty paperweight. Trust the label, not just the marketing photos of waterfalls and happy children.
