Reduced Operational Costs vs Final Water Quality – a Jar Testing Review


CWT undertook onsite jar testing to assess the viability of switching to a new coagulant at Mt Stromlo and Googong Water Treatment Plants (WTPs) to lower operational costs without compromising treated water quality for any raw water quality scenario.

Services Offered

  • Analysis of each source water to establish baselines (including blended source waters)
  • Coagulant dose optimisation and comparison of the current coagulants (alum and polyaluminium chloride) with aluminium chlorohydrate (ACH) for each WTP under differing raw water quality scenarios
  • Review of impacts of pre-alkalinity addition on coagulation
  • Modelling to identify post-dosing lime and CO2 requirements for pH correction and corrosivity control in final water supplied to customers
  • Modelling of relative sludge production for each coagulant option


Icon Water wished to lower operational costs through trialling alternate coagulants. Any reduction in cost needed to be balanced by any new risks to treatment capability (including downstream processes) and final water quality across varying source water qualities.


To achieve this CWT undertook onsite jar testing, simulating the different treatment processes and blended source water scenarios of the Mt Stromlo (direct filtration) and Googong (DAF) WTPs.


The results and recommendations allowed Icon Water to make an informed decision regarding coagulants, to ensure cost reductions were not achieved to the detriment of final water quality and public health outcomes.