Fully automatic filter system for the reduction of undissolved contaminants, with upstream oxidation stage also for the filtration of iron and manganese. With activated carbon filling for fining, odour improvement or chlorine reduction. Filter tank made of GRP, including aeration and ventilation and internal water distribution system. Filter front piping with pneumatic fittings and pilot valves. Flow meter for setting the filter capacity, differential pressure switch for triggering the backwash. Pre-assembled on an anodised aluminium frame with levelling feet.