Choose a treatment system only after defining the water problem and the demand it must serve. Every guide below is desk research from manufacturer documents and public guidance, and each one says where a laboratory result or qualified installer is needed.

Start with the water evidence

Well owners should begin with the well-water test panel guide ; a screen or TDS reading cannot identify every contaminant. Then read what a water test kit result does and does not tell you and use the NSF certification claim checklist before trusting a badge on a box. First-time well owners can use the well-water filtration checklist to organize records before buying.

Understand and size a whole-house system

What a whole-house filter is and how it works is the place to start. Calculate flow-rate requirements before choosing housing, media, or cartridge size, then work through capacity sizing for quotes , housing size , carbon capacity and sediment load . For odor and taste, see choosing a whole-house carbon filter . The placement guide covers where the system goes.

Pressure problems

Pressure and maintenance are separate design checks. Use the low-pressure diagnosis checklist and pressure-drop guide before blaming the treatment media. The pressure rating and pressure gauge guides cover the specifications, low-pressure wells have their own constraints, and installing an RO system on low pressure is a separate question.

Installation, maintenance and checking performance

Plan the job with the installation checklist , the housing readiness check and the filter-bypass guide . Keep records with the whole-house maintenance checklist ; for point-of-use units see kitchen filter maintenance and the replacement cartridge guide (pitcher, under-sink, RO and whole-house parts), and for RO systems the prefilter stage guide . To check results, see the home performance-test guide and the bucket flow test .

Hard water and softening

Start with choosing a system for hard water , then see using a softener to protect appliances , the brine tank capacity calculator and softener versus sediment filter order .

Reverse osmosis

The RO buying guide explains the system decision. RO versus whole-house filtration separates treatment process from location, and the recovery-rate and waste-water ratio guides explain how product-to-drain figures should be read. These guides do not treat filtration, softening, conditioning, and disinfection as interchangeable.

All guides

The water-quality report reading guide separates detected results, general health text and sampling scope before turning a report into a treatment question.

During a current notice, consult the filter and boil-water advisory guide ; an ordinary filter or certification claim does not exempt a household from the issuing authority’s instructions.