South Fork Water Treatment Plant

The City’s 2007 Water Supply Strategic Plan identified the provision of a safe, sustainable and affordable water supply with a multi-barrier approach while recognizing that water is a shared resource.

Traditionally the City supports water conservation including water metering of all properties and full cost pricing that places both peak and average day demands well below Provincial and National averages.

The South Fork Water Treatment Plant is a major initiative on several fronts

  • A key barrier in a multi-barrier approach
  • Provides safe drinking water that meets or exceeds current legislation to residents of Nanaimo
  • Strengthens partnerships with the Snuneymuxw First Nation and South West Extension

See the timeline and budget details from the 2015 project.

Nanaimo's New Water - Shaw TV Nanaimo

0:00 / 0:00

Nanaimo Water Treatment Plant Virtual Fly-Through

0:00 / 0:00



Drinking Water Regulations

New drinking water regulations implemented by Island Health adjusted the City’s Operating Permit to require filtration of the drinking water supply (also known as 4-3-2-1 Treatment Policy).

This means:

SFWTP reed beds
  • 4 - log (99.99%) removal of viruses that may be in the water
  • 3 - log (99.9%) removal of pathogenic organism (cryptosporidium and giardia lamblia) that may be in the water
  • 2 - log (99%) removal of viruses through forms of treatment (namely membrane filtration and disinfection with chlorine)
  • 1 - nephelometric turbidity unit (NTU) maximum turbidity in finished water

How is our water treated?

The new plant treats raw (untreated) water using the following process:

  • coarse screening
  • fine screening
  • chemical mixing (if required)
  • flocculation
  • ultra membrane filtration
  • ultra violet irradiation (secondary membranes only)
  • chlorine gas injection

Following filtration, a small amount of chlorine (1 part per million) is added to ensure that bacteria and viruses that may be present do not grow.

Please note: fluoride will NOT be added to the City's water. (Fluoride has never been added to the City of Nanaimo's drinking water.)

Water Treatment Plant Processes

The treatment process

The backbone of the water treatment plant process is a series of membrane filtration units – General Electric Water's Zeeweed 1,000 and 500 ultra-filtration membranes. These products were developed in Canada and are robust to handle variations in the City's water.

After flocculation water passes through Zeeweed 1,000 membranes and the water that is rejected from filtering will be passed through a second set of Zeeweed 500 membranes to capture as much of this precious resource as we can.

How fine are the membrane filters?

The size of the openings in the membranes are 0.1 micrometres, and this compares favourably to the size of various impurities (3-15 micrometres) that will be stopped from passing through, leaving pure, filtered water.

Water Treatment Plant Filtration System

Last updated: November 29, 2022

Help us improve our website

Don't include private or financial information in this form.

Collection and use of your personal information

Information collected on this form is done so under the general authority of the Community Charter and Freedom of Information and Protection of Privacy Act (FOIPPA), and is protected in accordance with FOIPPA. Questions about the collection of your personal information may be referred to the Legislative Services Department at 250-755-4405, or via email at Please also see our Privacy Policy.