Abstract: A water treatment dispensing apparatus for an engine cooling system, such as in a diesel locomotive, includes one or more probes for measuring the conductivity of the fluid circulating in the system. From the conductivity of the fluid, a determination of the level of concentration of treatment chemicals in the fluid can be ascertained. A comparator is utilized for determining whether, based on the conductivity readings of the fluid, the level of concentration of treatment chemicals in the fluid is at or above a desired level. When it is determined that the level of concentration has fallen below the desired level, a valve is actuated so as to divert a portion of fluid from the system to a chemical treatment dispensing apparatus. Simultaneously, an outlet valve is actuated to allow mixed fluid and chemical treatment to be routed back into the circulating system. The dispensing apparatus includes a housing adapted to receive a container for containing a quantity of chemical treatment therein.