Te Pūnaha Maimoatanga Wai o Ngāmotu

New Plymouth Water Treatment Plant

Source of water

Waiwhakaiho River

Present capacity

65,000,000 L/day


  • Coarse Material stepper screens at intake (Lake Mangamahoe)
  • Raw water conditioning (lime and/or CO2 addition).
  • Taste and odour removal (powdered activated carbon).
  • Coagulation (polyaluminium chloride).
  • Mixing (mechanical and static mixers).
  • Floculation (polyelectrolyte).
  • Clarification (upflow with gravelectric sludge removal cones).
  • Manganese/Iron removal (Lime for ph Adjust and Chlorine for oxidiation)
  • Filtration (rapid gravity filters).
  • Fluoridation (hydrofluorosilicic acid).

  • Disinfection (chlorine gas).
  • pH correction for minimise corrosion in the reticulation. (CO2 and lime).


Eight hopper bottom clarifiers fitted with plate settling tubes and gravelectric cones.


Eight rapid gravity sand filters filled with 600mm of anthracite over 400mm sand media.

The water treatment process