unidentified object under sink

[m8]

I've found a smallish transparent plastic drum shaped object under my sink, attached to the water supply and seems to be full of paper/crumpled up material...
Anyone got any clues as to what it might be and what it is meant to be doing there?

[e-richard]

I am told:

Its a filter that is supposed to reduce the chalk or limescale in the water.

You should replace the filter about twice a year. Switch off the water, and simply unscrew the glass holder, then comes the big question - where do you get the replacement filter ???

You have reminded me that mine needs replacing and I don't know the answer to my question

[m8]

Thanks - I bet you'll find some on the internet.
So it's a water softener...? rather than a filter to make the water drinkable......?