A water sediment filter removes suspended solids before they reach the rest of the house, and the choice between the three main types comes down to how much sediment there is and how fine it is. Get it right and every piece of equipment behind it lasts longer. Get it wrong and you are either changing cartridges every fortnight or wondering why the new filter changed nothing at all.
The three types and what each is for
A spin-down separator uses centrifugal action and a stainless screen to strip coarse grit, and it is flushed with a valve rather than replaced, which makes it the right front end on a well throwing sand. A cartridge filter in a housing catches the fine material and is the workhorse for most homes. A backwashing media filter holds a bed of graded media, cleans itself on a schedule and handles a heavy continuous load without any consumable, at the cost of a drain connection and more space.
Micron rating and staging
The rating describes the particle size retained, and choosing too fine is the most common error. A very fine cartridge on well water blocks in days and drags pressure down across the house. The professional approach is staging: a coarse cartridge first to take the bulk, then a finer one behind it to polish. That costs two housings and saves money immediately, because the cheap coarse cartridge absorbs the load that would otherwise destroy the expensive fine one.
Depth versus pleated versus string wound
Pleated cartridges have a large surface area, catch particles on the surface, and some are rinsed and reused a few times. Melt-blown depth cartridges are graded through their thickness, trapping coarse particles on the outside and fine ones deeper in, which gives far more dirt-holding capacity on variable water. String-wound cartridges sit in between and tolerate hot water and chemicals better. On a well with a variable load, depth is usually the longer-lasting choice.
Sizing by flow, and where it goes
Size to the household's peak flow with a generous margin, because pressure drop across a sediment filter rises steadily as it loads. A larger housing with a bigger cartridge is not finer, it simply holds more dirt before the pressure complaint arrives. The sediment filter goes first in the treatment train, ahead of the softener, the carbon and any UV, since every one of those is damaged or degraded by the particles it removes. Our best sediment filter for well water guide covers the well-specific choices.
Questions people ask about water sediment filter
What micron rating should I start with?
Start coarser than you think you need and stage down. A fine cartridge on unstaged well water blocks quickly and costs you pressure throughout the house.
Where does the sediment filter go in the system?
First, ahead of the softener, carbon filter and UV. Every one of those is protected by removing particles before the water reaches it.
Should I use a spin-down or a cartridge filter?
A spin-down handles coarse grit with a flush valve and no consumable. A cartridge catches the fine material. Wells that throw sand usually want both, in that order.
How do I know the cartridge needs changing?
Falling pressure at the fixtures is the practical signal. A pressure gauge before and after the housing turns that into a number you can act on early.