Water filtration for whole house coverage is a planning exercise before it is a purchase. The sound sequence is: find out what is in the water, choose the stages that remove exactly those things, put the stages in the right order, and size the whole train for the flow your household actually draws. Skip the first step and every later decision is a guess dressed up as a plan.
Step one: get the evidence
City households start with the utility report and confirm anything doubtful with a home test; well owners must test because no one else monitors a private supply. The test drives everything, including for newer contaminants: in 2024 the EPA set maximum contaminant levels of 4.0 parts per trillion for PFOA and PFOS and 10 parts per trillion for PFHxS, PFNA and GenX, and May 2026 proposals keep the PFOA and PFOS limits with a compliance option to 2031 while proposing to rescind the others. If PFAS shows in your report, that finding changes which media belongs in the plan.
Step two: order the stages correctly
Filtration stages are ordered so each protects the next. Sediment always comes first, because grit blinds carbon and fouls resin. Iron and sulfur treatment comes next where the water needs it, since oxidized iron destroys downstream media beds. Carbon follows for chlorine, taste and odor. A softener, where hardness justifies one, sits after filtration so it receives clean water. UV disinfection goes last, because the lamp needs clear water to work. This order is not a preference; reversing any pair of stages makes the earlier one do the later one's damage.
Step three: size for flow, then buy
A whole-house train must pass the flow of a busy morning without choking: showers, a washing machine and a faucet at once. Every serious vendor publishes flow ratings per model; Aquasana lists its whole house range with capacities and stage layouts on the category page, which is the kind of specification to compare rather than marketing copy. Size to the peak, not the average. When the plan is set, our best rated whole house water filtration system guide compares the current hardware against exactly these criteria: stage flexibility, honest flow ratings and maintenance cost over the system's life.
Questions people ask about water filtration for whole house
What order should whole house filtration stages go in?
Sediment first, iron or sulfur treatment where needed, carbon next, softening after that if hardness demands it, and UV last. Each stage protects the one behind it.
Should I test before buying whole house filtration?
Always. A test tells you which stages you need and which you can skip. Buying a generic package without one means paying for the wrong treatment surprisingly often.
Can whole house filtration deal with PFAS?
Specific media and system designs target PFAS, and the EPA has set enforceable limits for several PFAS compounds. If your report shows them, choose equipment tested for that removal claim.
How do I avoid pressure drop across the system?
Size each stage to your peak household flow using the manufacturer's published ratings, and maintain cartridges on schedule. Undersizing is the usual cause of weak showers.