Backflush filters clean themselves by having water pushed the other way through the element, or by having accumulated material dumped out of a chamber, rather than by being thrown away and replaced. That makes them cheap to run and limited in what they can do, and both of those follow from the same design choice.
What backflushing actually cleans
These filters retain material at a surface: a stainless mesh screen or the wall of a spin down chamber. Because everything is held at the surface rather than through the depth of a media, reversing the flow or opening a purge valve releases it in one go. That is why they can be cleaned indefinitely. A depth filter such as a melt blown cartridge holds material throughout its thickness and cannot be recovered this way, which is why those are consumed instead.
The limit that comes with it
Surface retention means a screen, and a screen fine enough to catch silt blocks almost immediately at household flow. So flushable filters live at the coarse end: they catch sand, grit, rust flakes and pipe debris and pass fine silt and clay entirely, along with everything dissolved. They are a first stage that protects what follows, never a substitute for finer filtration, and expecting one to clear cloudy water is the usual disappointment.
Manual against automatic
A manual unit needs someone to open the valve on a schedule, and a filter that is purged when somebody remembers spends much of its life full and passing everything through. Automatic versions add a motorized valve and a timer, which removes the one maintenance task these have, and add a power supply and a moving part in gritty water that can stick. The honest question is whether the manual purge would actually get done in your installation.
Installing one
First in the train, immediately after the pressure tank on a well, so grit never reaches the media tanks, softener, membrane or ultraviolet downstream. Route the purge to a drain that will take a slug of water and grit without blocking, with a short falling run. Protect both the body and the purge line from frost in an unheated pump house. And expect a cartridge or media stage after it for the fine material it passes. Our whole house filter guide covers the staging.
Questions people ask about backflush water filter
How can a backflush filter be cleaned indefinitely?
It retains material at a surface rather than through a depth of media, so reversing flow or opening a purge releases it all.
Why will it not clear cloudy water?
Surface retention needs a screen, and a screen fine enough for silt blocks immediately. These catch grit, not fine silt.
Manual or automatic purge?
Automatic removes the only maintenance task and adds a power supply and a moving part. Manual works if the purge actually gets done.
Where does it go in the system?
First, after the pressure tank, so grit never reaches the media tanks, softener, membrane or UV downstream.