Water treatment for dialysate preparation

Water pretreatment apparatus for a dialysis machine, said dialysis machine having a water inlet, comprising:

• a fluid line connected to a source of water and conducting water from said source of water through said water pretreatment apparatus, said fluid line having placed therein:
• (i) a carbon filter through which water flows from said source of water;
• (ii) a polyphosphate water conditioning agent through which water flows from said source of water;
• and
• (iii) a pressure regulator downstream of said carbon filter and said polyphosphate filter;
• said pressure regulator controlling the pressure of water supplied by said water pretreatment apparatus to said dialysis machine;
• and
• a drain line supplying drain fluids from said dialysis machine to said water pretreatment apparatus to a drain;
• a water input connection and a water input line connecting said water input connection with said water inlet of said dialysis machine;
• wherein said dialysis machine further comprises a drain outlet and said pretreatment apparatus further comprises a drain input connection, said drain line connected between said drain outlet and said drain input connection;
• and wherein said dialysis machine further comprises a user interface periodically prompting a user of said dialysis machine to periodically switch said water input line with said drain line wherein said drain line connects said water input connection to said water inlet and said water input line connects said drain outlet to said drain input connection;
• whereby bacteriological growth in said water input line is minimized.