 The used rinse water empties into the wash tank reservoir, which dilutes some of the used wash water and causes a small amount to drain out through an overflow tube.The system may first rinse with pure water only and then sanitize with an additive solution that is left on the dishes as they leave the washer to dry.Additional soap is periodically added to the main wash water tank, from either large soap concentrate tanks or dissolved from a large solid soap block, to maintain wash water cleaning effectiveness.