Use the coarsest filter that reliably removes the sediment you need to stop, then add finer stages only where necessary.
What a micron rating means
A micron is one-millionth of a meter. A nominal micron rating describes approximate particle capture; an absolute rating is a stricter specification.
Manufacturers do not always use the terms consistently, so check the product data rather than comparing only the number on the package.
Typical use cases
A 20–50 micron stage can be useful for coarse sand, rust flakes and larger sediment. Five microns is common as a final whole-house prefilter before carbon or softening equipment. One micron is much finer and can clog rapidly on dirty water.
Spin-down filters are often used upstream where heavy sediment loads would destroy disposable cartridges quickly.
Pressure drop matters
Every filter adds resistance. As sediment loads into the media, pressure drop increases. A filter that is too small for the flow rate can make showers and fixtures noticeably weaker.
Size both the housing and micron rating for peak household flow, not just average daily use.
Sediment filters do not remove dissolved contaminants
A sediment cartridge can remove particles but not dissolved hardness, nitrate, PFAS or most dissolved metals.
Use sediment filtration as pretreatment, not as a substitute for contaminant-specific treatment.