Conventional water treatment plants

Conventional water treatment plants

SA Water’s conventional water treatment plants typically use a seven step process to deliver safe drinking water to our customers. A listing of our conventional water treatment plants can be found here .Those steps are:

  1. Coagulation
  2. Flocculation.
  3. Sedimentation.
  4. Filtration.
  5. Disinfection.
  6. Fluoridation
  7. Storage and distribution.

Let's look at what each step involves.

Water treatment process

1. Coagulation

A chemical (coagulant) is added to the untreated raw water and reacts with impurities such as small particles and dissolved organic matter. The coagulant traps the suspended particles and much of the dissolved organic material. The success of the treatment process very much depends on successful coagulation and SA Water is investing in the latest instrumentation to help maximise coagulation effectiveness.

2. Flocculation

The coagulant combined with the captured particles is called ‘floc’. Flocculation is a gentle mixing process that brings together the flocs formed in the coagulation step to form larger flocs that settle more easily. Water remains in the flocculation tanks for a minimum of 20–30 minutes

3. Sedimentation

Water and suspended flocs pass slowly through sedimentation basins or clarifiers, where most of the floc settles to the bottom as a sludge. The clarified water (now containing only a small amount of very fine floc particles) continues on to the filters. The sludge is periodically removed from the basins for further treatment and disposal. An alternative technique called Dissolved Air Floatation (DAF) is used at the Myponga Water Treatment Plant. This uses fine air bubbles to float floc to the surface to form a sludge blanket, which is periodically removed by overflowing the floatation tanks.

4. Filtration

The remaining floc particles are removed by passing the clarified water through filtration media. The most common filters at the larger water treatment plants are deep beds of sand or a combination of sand and anthracite. In our newer and smaller water treatment plants, the final filtration step is achieved by forcing the clarified water through synthetic membranes.

5. Disinfection

A chemical disinfectant is generally added at a point between the filters and the filtered water storage tank, to destroy any microorganisms that may not have been removed in the earlier flocculation and filtration stages. In South Australia, chlorine is the disinfectant of choice for supply systems with relatively short detention times of a day or two, while chloramine (produced by reacting chlorine and ammonia) is used in supply systems with longer pipeline infrastructure. Disinfection sometimes requires the pH of the water to be adjusted to enhance the performance of the disinfectant. In some applications, ultraviolet (UV) light is used to complement chemical disinfection.

6. Fluoridation

Fluoride is then added on behalf of the SA Department of Health and Ageing in order to provide a significant public health benefit. Fluoride does not affect the appearance, taste or odour of drinking water and is controlled to ensure levels comply with the Australian Drinking Water Guidelines.

7. Storage

Drinking water can then be stored in storage tanks. Tanks are strategically located to deliver water more effectively during peak usage times.

  • Major faults

  • Reported

  • Grand Junction Rd
  • Northfield
  • 02/04/2020
  • Water Supply Interrupted
  • Last Updated: 02/04/2020 08:17 AM - We are on site in Northfield and the nearby water supply may be unavailable until 02/04/2020 01:00 PM. Sometimes our crews need to temporarily interrupt the water supply to our customers and/or manage traffic while they are working. We always aim to minimise inconvenience by restoring supply as safely and quickly as we can. Reference Number WO: 07403027.
  • See all major faults

  • Scheduled works

  • Underway
  • Ashbrook Av
  • Payneham
  • 02/04/2020
  • Temporary Supply Interruption
  • Estimated start time and water supply off: 03/04/2020 09:00 AM
    Estimated restore time and water supply back on: 03/04/2020 06:00 PM

    We’re improving your services and undertaking maintenance work in Payneham. Sometimes our crews need to temporarily interrupt the water supply to our customers and/or manage traffic while they are working. Temporary traffic management may remain in place until reinstatement of the impacted road is complete. We always aim to minimise inconvenience by restoring services as safely and quickly as we can.

  • See all scheduled works