Potential phone delays

9:00AM 01 Jun 2023

Thanks for your patience if you experience a delay when ringing our call centre. Please email us on enquiries@npdc.govt.nz or drop into one of our offices. 

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).
  • 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