Carbon Filter Non-Backwashing System

Carbon Filter Non-Backwashing System

Carbon Filter, In/Out Unit

This tank-style filter is a non-backwashing carbon filter that is often called an "In/Out" filter". It is a great solution for wide variety of water related issues where backwashing is either restricted or not possible. Since it doesn't have to backwash, you can put more carbon in the tank.


  • Clack In/Out Head with bypass installed
  • For city or municipal water applications
  • Reduces chlorine taste and odor
  • No electricity required
  • No drain required
  • Tank size: 23cm x 122cm (9” x 48”)
  • Media: 1 cu. ft. activated carbon

Learn More

How an In/Out unit works

More about In/Out style filters

In/Out filters are inexpensive as compared with backwashing filters. Their simplicity also makes them attractive alternatives to backwashing filters in many situations. Their use is limited, however, mainly to use as dechlorinating filters for city water and for neutralizing filters for acidic well water. Plus, the water they treat must be clean, so it's wise to always install a sediment filter in front of an in/out filter.
In/Out filters do not work as iron filters, because a backwash function is needed to get rid of the trapped iron. Likewise, they do not work as sediment filters and must, as noted, be protected from sediment when they are used as city water dechlorinating filters or as neutralizing filters for wells.
In/Put filters actually have an advantage over backwashing filters for city water dechlorination in that more media can be loaded in the tank since freeboard space does not have to be left at the top of the tank to accommodate backwashing. For example, a 10" X 54" backwashing filter can be loaded with 1.5 cubic feet of carbon, but a 2.0 cubic foot bed works well in an In/Out filter.
In most filter designs, with simple filters like those shown on this page a downflow filter can be installed as an upflow filter simply by reversing the direction of flow into the tank.

How long will the carbon last before I have to change it?

The many variables--flow rate, amount of disinfectant, other factors in the water, the number of gallons of water used--make it impossible to give a precise answer, but in normal residential filters a three or four year service life of the carbon is a reasonable expectation. It can be much longer if conditions are right.

Is changing the carbon a hard job?

In general, it isn't a hard job, but it can be a messy job. It depends on where the filter is installed. If it's accessible, it's a matter of screwing the top off of the filter, like screwing the lid off of a bottle, pouring out the contents, and pouring in new carbon. The carbon is the consistency of coffee grounds, but there's a lot of it, and when it's wet, it's heavy.