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R9 Laboratory SOP 825
DEIONIZED WATER MONITORING
Summary
This standard operating procedure has been developed to assure the quality of reagent water used for method blanks, sample dilution, glassware cleaning, and other analytical tasks at the EPA Region 9 laboratory. The laboratory utilizes a primary deionized water system which consists of a water softening unit followed by an activated carbon bed and then a reverse osmosis unit followed by holding tank. Water circulates from the holding tank to five mixed ion beds (in parallel), through an ultraviolet light treatment and then a membrane filter. The water is then circulated throughout the laboratory back to the holding tank. A separate loop provides chilled water for cooling laboratory instrumentation. The primary deionized water is constantly recirculated and treated. The primary system is designed to provide the laboratory with Type I reagent water although the laboratory is currently monitoring it in compliance with Type II criteria. There are also eleven ultra high purity water systems (also referred to as polishing units) designed to provide organic-free Type I reagent water located in rooms throughout the laboratory which use the primary deionized water as the feedwater and remove very low level contaminants using a mixed-bed deionizer and a membrane filter. In order to monitor the quality of the deionized water, the primary system is sampled daily at two random locations throughout the laboratory to assure that water from the deionized taps in the laboratory rooms meets criteria.
The three ultra high purity systems which are in frequent use are also monitored daily. The other eight units are labeled as "out-of-service" and a brief description of the procedure required bring the systems on line is attached. All monitoring is for conductivity, which will be very low if the water has no ionic contamination.
The EPA Region 9 laboratory uses conductivity as a measure of reagent water quality. The primary deionized water system is monitored daily at two locations and the water polishing units in service are also monitored daily. Some water polishing units are out of service and are posted as such. Monitoring includes any observations by the analyst of the condition of the system such as resistivity reading, system error lights, or unusual noise during operation, and a conductivity analysis. Records are maintained in a logbook to demonstrate quality and determine any trends. Maintenance of systems is also noted in the logbook.