Any household that goes through more than a couple gallons of drinking water a day will probably be happiest using an under-sink filtration system, like our pick, the Aquasana Claryum 3-Stage Max Flow. That’s because, unlike filter pitchers, under-sink filters provide a continual supply of water on demand. You can fill a glass in a few seconds any time you want, or a pot or pan when you’re cooking.Of the under-sink filters we’ve reviewed, the 3-Stage Max Flow’s certifications are among the very best. They include chlorine, chloramine, lead, mercury, PFAS, volatile organic compounds (VOCs), multiple pesticides, and microplastics. (In fact, all of our picks carry the same 78 NSF/ANSI certifications for contaminant removal.) Compared with most filters of its kind, the 3-Stage Max Flow delivers water more quickly, and it has fewer clogging issues.