Full Text
General Guidelines for Public Water Supplies Operating Hypochlorination Disinfection Systems Cortland County Health Department Chlorinator Operation • Daily measurement of free chlorine residual must be done. This must be reported on the daily operation report form provided by the Health Department. • Chlorine residuals must be greater or equal to 0.2 mg/L. If the chlorine residual is below 0.2 mg/L, adjustment to the system must be done immediately to raise the residual to 0.2 mg/L or greater. If this cannot be done, the facility must notify the Health Department and will be placed on a Boil Water Order (BWO). BWO guidelines shall be followed (see separate guidelines from the Health Department). • It is recommended to keep the free chlorine residual in the range from 0.5 to 0.8 mg/L. The maximum allowable level of free chlorine residual is 4.0 mg/L. This is quite high, as system in Cortland County rarely exceed 1.5 mg/L free chlorine residual. • Use the correct DPD powder/pill and volume of water when sampling. DPD powder/pills are available for both free and total chlorine residual. Measurement and reporting is for free chlorine residual. DPD kit manufacturers require various volumes of water for measurement. Check kit to make sure correct volume is used (e.g. 5 ml, 10 ml, or 25 ml). Most kits use 5 ml volumes for sampling. • Chlorine Solution: recommended solution strength is 4 to 8 oz. (1/2 to 1 cup) of Clorox into 5-10 gallons of water in solution tank. Chlorinator Maintenance • Clean chlorine solution tank (crock) (remove scale and sediment buildup) • Clean chlorination pump: head, filters, valves and tubing semi-annually. • Service chlorination pump annually. May require pump head replacement. 23 February 2005 \\Doc2\Divisions\Environmental\Environm\WPDATA\water\publicwatersupplies\chlorination general operation guidelines.doc