The invention concerns a water purification system (100) comprising a closed water recirculation loop (106) supplied at one point by a water inlet (101) with water to be purified, (and having) at least one outlet point of use of the purified water (102) and (further comprising) pumping means (103) and water purification means (150) on the loop respectively downstream of the inlet point and upstream of the at least one outlet point (102), in the water flow direction which system is characterized in that it includes two independent valves: a first valve (130) on the loop upstream of the pumping means (103), and a second valve (120) upstream of the at least one point of use outlet point (102). The invention also relates to a water purification method.