AWWA PATH56548

The Water Supply (Water Quality) Regulations 1989 in the United Kingdom were amended in 1999 to include the continuous monitoring of drinking water for Cryptosporidium. The amended Regulations require the presence of less than one oocyst in 10 litres of drinking water based on a 1,000 litre sample, taken over a 24 hour period. An initial trial to run the EnvirochekTM STD alongside the Genera Filta- MaxTM proved unsatisfactory. This was because under high headloss pressure the filter became damaged and the amount of deposit recovered was half that of the Filta- Max. Pall has now modified the original filter and named this the EnvirochekTM HV. Filter modification has shown through testing to eliminate filter collapse at both high differential pressure and changes to flow. The filter was evaluated using three differing types of treated water: an upland water; a lowland water; and, a borehole supply. All three sites were monitored continuously, over a period of 60 days, at a flow rate of 1,000 litres per day. The EnvirochekTM HV was run alongside the Filta-MaxTM on 10 days out of the 60 day period. Filters were seeded with a known quantity of oocysts daily and where both filters were run alongside each other, the same test conditions were used. The evaluation included 48 hour sampling at each site and bias testing where the oocyst concentration used to seed the filters was varied. Negative controls were run at the same time for both products. Additional data collected included the flow through the test filter after 24 hours and the measurement of the differential pressure across the EnvirochekTM filter over the test period. On completion of the sampling period, the samples were then transported back to the laboratory for analysis. Oocysts were eluted from the filters using a standard operating protocol, concentrated by centrifugation and cleaned from unwanted particulate matter by immunomagnetic separation. The sample was then spotted onto slides and fixed with methanol, stained with a monoclonal antibody and then counted. Includes 19 references, figures.