A connector for connecting a dialyzer to a hole in a side wall of a water pipe, the connector including a connector body including a cavity crossing the connector body from a first end of the connector body to a second end, for enabling water flow from the first end to the second end, wherein the cavity at the first end is shaped and sized for pressing onto a port of a dialyzer, and the cavity at the second end is shaped and sized for pressing into a hole in a side wall of a water pipe. In a water filtration system including dialyzers for water filtration, a method of cleaning a dialyzer including providing clean water from a clean water output of one first dialyzer to a clean water output of one second dialyzer, to backwash the second dialyzer. Related apparatus and methods are also described.