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Reservoir Water Quality Improvement

After looking into various options to minimise water quality issues, we are considering installing active reservoir water mixers in all of Napier’s drinking water reservoirs.

These mixers are motorized submersible jets and propellers that create a vortex flow inside reservoirs to circulate the entire volume of water.

They are useful to:

  • Eliminate thermal stratification (of water layers)
  • Improve overall water quality
  • Reduce water age and residual loss.

Water storage reservoirs throughout New Zealand are susceptible to variable temperature layers, loss of chlorine, bacteria and biofilm regrowth, and taste and odour issues.

These water quality issues are a result of when the reservoirs are relatively full and the incoming new cold water from the bores sit at the bottom and warmer water sits at the top. The lower layer of cold water exits the reservoirs first, flowing to homes and businesses. 


Design stage 



Estimated timeline:

December 2021


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