Gippsland Water’s main objective is to ensure our customers receive safe drinking water at all times. Our drinking water is assessed against the Safe Drinking Water Act (SDWA) 2003 and the Australian Drinking Water Guidelines 2004 to ensure compliance against these stringent drinking water quality standards. The results of our annual drinking water monitoring program are reported to the Department of Human Services (DHS) under the SDWA 2003 as part of our Annual Regulatory Reporting framework.
Safe drinking water is water that does not cause illness to those who consume it. To confirm this, an independent laboratory monitors the water Gippsland Water supplies, measuring it for bacteriological, physical and chemical parameters. The water must be free of pathogens and free of harmful chemicals at all times.
Cleaning water to make it safe to drink
In order to achieve the objective of providing safe drinking water at all times to our customers the raw or untreated water sourced from catchments, rivers, streams and groundwaters (bore water) must first be treated to ensure it meets the safe drinking water standards. The treatment involved to produce safe drinking water involves the following process:
Pre-treatment
Raw or untreated water can be slightly acidic (pH <6.5) due to the natural influence, so alkaline (pH >8.5) such as lime, soda ash etc may be added during the initial treatment stage to correct pH so optimum conditions for the coagulation process can efficiently take place.
Coagulation
Coagulation is the process to remove very fine suspended particles often associated with turbidity, colour or colloidal water. These particles have a negative charge that causes them to repel each other. The addition of a suitable coagulant of iron and or aluminium salt with a positive charge neutralises or destabilises the negative charge enabling the fine particles to join together to form larger particles.
Flocculation
The flocculation process involves stirring the water gently after the coagulant has been added. This helps to move the material around which eventually causes it to stick together (floc). This process removes the fine particles, dirt and colour present in the water.
Clarification/sedimentation
The clarification or sedimentation of the flocculated (floc) materials is usually carried out under still conditions (eg sedimentation tank or clarifier). A sedimentation tank relies on gravity to separate the floc, which is heavy and falls to the bottom of the tank - leaving the 'cleaner' water on top. A clarifier uses a mechanical process to separate the floc from the waters and the water is collected in troughs at the surface. Once the floc has been removed the clean (settled) water is sent to filters.
Sludge removal
Sludge produced in the clarification or sedimentation process is transported to a separate holding tank where it is de-watered to a solid state, removed and then transported to a disposal or beneficial re-use facility. The sludge comprises a high percentage of solids, particulate matter and colour removed from the raw or untreated water that enters the water treatment plant.
Filtration
The clarified water is passed through a filter media consisting of several types of graded filter media (sand, gravel, charcoal or plastic beads) to remove any remaining particles, floc or dissolved chemicals that may have passed through the clarification/sedimentation process.
Over time the filters gradually become clogged with trapped particles and floc. A filter backwash is then carried out to clean the filters, returning them to optimum condition using air and water forced up through the filter nozzles to agitate the filter bed and remove any trapped particles. The final turbidity leaving the filters during normal plant operation is less than 0.1 NTU (unit that measures turbidity).
The backwash water produced during the filter cleaning process is discharged to the sludge thickening system to separate solids from process water. To optimise water efficiency the separated process water is then returned to the treatment plant and mixed with new raw water to recommence the treatment process.
Disinfection
Drinking water is disinfected to prevent the spread of water born pathogens (bacteria) that cause disease such as dysentery, cholera, typhoid and gastroenteritis. A low residual level of disinfection also ensures that the water remains 'safe' once it leaves the water treatment plant until it arrives at the customer’s tap. In Gippsland Water's service area, chlorination is the most commonly used disinfectant because of its safeness, reliability and cost effectiveness. Chlorine is also the most widely used disinfectant for water supplies in the world. The other disinfection treatment processes used in our region is chloramination.
Fluoridation
Fluoridation is part of the treatment process for the following of Gippsland water’s water supply systems: Maffra, Stratford, Moe, Morwell, Traralgon, Sale, Warragul and Drouin.
Water quality
What makes water look dirty?
Water looks dirty due to two main components:
The colour in the water is generally created by the naturally occurring tannins that leech from trees and inorganic material such as bark and humus. Colour gives water its ‘tea-like appearance’.
Turbidity on the other hand is the insoluble particles including dirt, soil, colloidal material and organics that are suspended in the water.
Both colour and turbidity have no direct impact on health, instead they tend to be removed due to aesthetic reasons. Consumers do not like drinking a discoloured glass of water as they form the opinion that it is contaminated, even though it may not be. Therefore, colour and turbidity are removed during the water treatment process. |