Use of microbiological indicators to classify recycled water It is not possible to monitor recycled water for every pathogen that may occur in untreated sewage, for this reason, indicator species are monitored as a measure of treatment effectiveness. E.coli is the thermotolerant coliform species most commonly found in human waste, is generally accepted as being a suitable indicator of reduction of bacterial pathogens in recycled water before storage. Clostridium perfingens is used as an indicator or removal of protozoan parasites from recycled water. Coliphages (Phages) are considered the most useful viral indicators for sewage treatment - a treatment process that reduces phage concentrations to very low levels can be expected to remove virtually all pathogenic viruses. Advanced recycled water treatments like membrane filtration can reduce 100,000 virus particles per 50 litres down to less than 1 virusm per 50 litres. Membrane Filtration as can be seen in the above graph is the most effective in reducing all pathogens and organisms in recycled water, with the highest level of reduction in all categories.. Chlorination is indicated as being ineffective for the reduction of viruses, Phage, Giardia, Crypto, Clostridium perfingens and Helmiths. E.coli and Bacterial Pathogens it is more effective, however its range of effectiveness is very broad. Ozonations range of effectiveness is broad, data does not currently exist for its effectiveness on Giardia, Crypto or Helmiths. Ozonation is relatively ineffective for Clostridium perfingens. For Ultraviolet disinfection difficuties may arise in wastewater containing a high amount of suspended solids. For all pathogens and organisms, UV light is only relatively effective, with its strongest reduction being of Phages. But again this is very broad. Detention Lagoons is relatively ineffective in all areas.