Development of a generic monitoring protocol for management of Cryptosporidium and Giardia in drinking water
Sigudu, Makhosazana Victoria
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In South Africa, the assessment of the suitability and acceptability of water for drinking purposes is done according to the South African National Standards (SANS) 241 (2006) which requires that Cryptosporidium and Giardia in drinking water should be less than 1 oocyst/10l and 1 cyst/10l respectively. Although there is a requirement to monitor for these parasitic protozoans, there is lack of uniformity in the monitoring approach. Therefore, the objective of the study was to develop a protocol/methodology that can be applied by drinking water producers to monitor Cryptosporidium and Giardia to ensure that the risk of exposure to these organisms and the risks of non–compliance to guidelines are reduced. Also, to test the feasibility of the protocol on a small system, the drinking water purification plant at the Vaal River Barrage Reservoir that supplies approximately 350 people with drinking water. The protocol for monitoring of Cryptosporidium and Giardia was developed based on monitoring procedures proposed by the US Environmental Protection Agency, the Drinking Water Inspectorate, Australia, New Zealand, and especially on the risk based procedure followed by Northern Ireland with the intention that it will be applicable to all water supply systems irrespective of size and system complexity of the purification works. It is focused on a preventative approach of monitoring Cryptosporidium and Giardia and it consists of ten steps which are: (i) Assessment of the monitoring requirements, (ii) Description and characterization of the source water types (iii) Abstraction of source water (iv) Assessment of the water purification plant (v) Water quality monitoring (vi) Cryptosporidiosis and Giardiasis outbreak (vii) Risk assessment (viii) Sample collection and Laboratory processing (ix) Data evaluation, interpretation and storage (x) Process evaluation and review. As stated, the developed protocol was tested at a small purification plants situated at the dam wall of the Vaal River Barrage catchment, Gauteng Province . From this assessment it was evident that steps of the protocol were easy to follow and the possible risks in the water value chain i.e. from source water to the supply of purified drinking water could be identified. Some of the challenges encountered during the application of the protocol include difficulty in obtaining detailed information regarding the activities around the catchment and information on the prevalence of cryptosporidiosis and giardiasis in the local community or in South Africa in general. From this study, it could be concluded that the source water from the Vaal River Barrage Reservoir was high risk. However, the use of the multi–barrier approach coupled with advanced treatment of UV rendered the water drinking supplied to the local community within the South African Drinking Water Standards for from Cryptosporidium and Giardia of less than 1 oocyst/10l and 1 cyst/10l. The protocol for the monitoring of Cryptosporidium and Giardia could contribute to the protection of drinking water consumers by identifying high risk source waters, identifying areas that can be improved in the water treatment system and also protecting the catchment areas from further faecal pollution. With respect to this outcome, the developed protocol could be used by water utilities as part of their Water Safety Plans to optimize monitoring. Furthermore, this methodology has a potential to contribute to the blue drop certification as it should for part of the Water Safety Plans.