The filter consists of two internal subunits; one half is ultrafiltration threads and the second is activated carbon. Unlike other activated carbon filters that initially produce a black residue, this one does not exhibit such a thing, although continuous flow for 5 minutes before first use is recommended. It is by far the best and highest quality drinking water filter I have tried. In combination with a triple filter of mesh - thread - and expanded polyethylene that I have in the main supply, the filter truly delivers crystal-clear water and lasts about 16 months for a family of four. Without prior filtration of the main supply or some pre-filter, a significantly reduced lifespan is expected as it will also take on the filtration of other particles, mud, and whatever else circulates within the water supply pipes.
