Abstract: A chlorinator includes an electrode assembly and a housing. The housing includes a first water flow opening, a second water flow opening, an electrolysis chamber for accommodating the electrode assembly, a sampling chamber for selectively enabling sampling of water entering the housing in operation of the chlorinator, and a flow stream separator. The flow stream separator includes a partition wall axially extending between a first partition edge and a second partition edge. The partition wall separates the housing internal volume into a main channel and an auxiliary channel. The main channel extends axially between the first partition edge and the second partition edge, and wholly accommodates therein the electrolysis chamber on a first side of the partition wall. The auxiliary channel extends axially between the first partition edge and the second partition edge and wholly accommodates therein the sampling chamber on a second side of the partition wall.