Water Quality Awareness 101 5 | P a g e  Test for fluoride levels of mains if unsure which is the raw water (for raw water systems and systems with fluoride dosing only)  Utilise calibrated in-line analysers to measure chlorine residual Maintenance Considerations:  Have separate clothing and tools for use on jobs on drinking water systems only  Wash and disinfect old or restored parts and fittings before installing them on drinking water systems (tag clean items whilst in storage)  Ensure an adequate chlorine/disinfectant residual is present after any repairs to drinking water mains to guarantee disinfection  Flush any water pipes or mains after the completion of works to remove any debris, sediment or contaminants and restore adequate disinfection levels  Test back flow prevention devices regularly (have a testing program in place for high risk customers and chemical dosing or transfer lines) 6. CHEMICALS Chemical contamination of drinking water, or water intended for use as drinking water, can be both direct and indirect. Direct contamination can come from paints, oils, lubricants etc. that can be introduced inadvertently, or deliberately into drinking water systems. Indirect introduction could occur through maintenance or wash down activities that are undertaken in, on or around drinking water storages, assets or systems. Contamination from maintenance practices are the most common cause of chemicals inadvertently entering drinking water systems. They are also the easiest to avoid by following a few basic precautions. 6.1.1 Issues  Petrol and oils from machinery used during construction and maintenance on or around drinking water systems  Weed spraying undertaken near or around a drinking water treatment process or storage, raw water off-take pipes, or in the catchment, where there is the potential of runoff into the source water  Paints used in a water treatment plant, water storages and the distribution network that are not compliant with the requirements of AS4020:2005: Testing of products for use in contact with drinking water  Greases from machinery and tools used during the construction, operation or maintenance of drinking water systems  Lubricants for fittings and drinking water system parts, such as valves and pipework that are not approved under AS4020 for contact with drinking water