Water for Portland, Port Fairy and Heywood is sourced from the Dilwyn Aquifer. This is a deep underground geological formation that stretches across South West Victoria and into South Australia.

The Dilwyn is one of the most substantial and reliable water sources in Victoria due to its massive storage. Its depth means that it’s isolated from the effects of climate change and land use. It’s also isolated from more shallow aquifers by layers that prevent water moving from one aquifer to the other.

The Dilwyn Aquifer comprises strongly confined quartz sand that is up to 1.5 kilometres deep in places. The water in the aquifer is very old, having fallen as rainfall between 900 and 30,000 years ago.

Because the water comes from deep underground, it has naturally occurring mineral salts which can impact the taste. All the drinking water we supply is safe and monitored to ensure the quality meets the health standards as specified by the Australian Drinking Water Guidelines.

This is caused by the natural minerals, particularly calcium and magnesium carbonate, which can remain after the water has evaporated.

When we reduce the amount of mineral salts in the water supply, we expect that any salty residue will be eliminated consistent with experience in other areas where the water quality is better.

When the water is heated, the minerals are deposited as scale. This can affect kettles, hot water services, dishwashers, pipes and fittings. Scale is harmless, but will build up over time.

When groundwater from the Dilwyn Aquifer is extracted, it can range from 37 to 60 degrees celsius in temperature. We treat the water to help remove small amounts of minerals, such as iron and manganese.

It’s then aerated, which helps to remove some organic odour compounds, and cooled to lower the temperature to between 23 and 26 degrees celsius. The water is disinfected using chlorine or sodium hypochlorite to maintain safe drinking standards while it’s stored in tanks or basins ready for distribution to our customers.

Reverse osmosis is a process that uses enormous amounts of pressure to force salty water through a membrane (a filter with microscopic holes). The salt molecules are generally too big to squeeze through the holes but the water molecules are small enough to pass through. This leaves most of the salt on one side of the membrane and fresh water on the other side.

We assessed multiple options for all three towns in 2022. We concluded that adding filtration (reverse osmosis) to the local groundwater is the preferred approach to reduce the saltiness to levels similar to our other water supplies across the region.

By reducing the amount of salt in the water supply below the taste threshold for most people (<300 ppm), we expect that the water will be high quality drinking water, similar to other surface water supplies across our region .

It will produce high-quality drinking water that meets our strict quality requirements including standards set by the:

• Australian Drinking Water Guidelines
• Victorian Safe Drinking Water Act
• World Health Organisation.

Aeration is part of the process for cooling the existing groundwater supplies. The filtration process we plan to use to remove salt is commonly used to produce high quality drinking water.

SA Water has recently completed a similar project for the outback town of Oodnadatta: https://www.sawater.com.au/news/historic-upgrade-delivers-oodnadattas-new-water

There will be no additional cost to customers. The Federal Government announced $26.1 million in its 2023 budget to support us to improve the water quality in Heywood, Port Fairy and Portland. The funding, from the National Water Grid Fund, follows years of planning and extensive community, stakeholder and government engagement. We’ll be borrowing money to match the funding allocation.

A routine maintenance program will ensure the filtration plants continue to work well. Routine maintenance is a normal part of operations at all our existing water treatment plants. The filters undergo regular automated cleaning as part of normal plant operations, and from time to time they need replacing.

Ongoing maintenance costs have been allowed for in our planning.

Filtration will remove naturally occurring mineral salts in the groundwater. Known as ‘brine reject’, this removed salt will be sent to mix with the salty ocean through our licensed discharge points at Portland and Port Fairy.

At this stage, it’s expected that we’ll tanker it through to Portland where it will be discharged to the ocean outfall. However, this won’t be confirmed until the final treatment method for Heywood is approved.

As part of the federal funding agreement, water quality improvements in all three towns need to be completed by 2029. We won’t have a specific timeline until the design and approvals are finalised.

Local treatment allows installed capacity to better match demand, providing a more efficient investment. Demand growth can be accommodated with modular increases if required.

The demand for recycled water will in part depend on its quality. For most re-use applications, a key consideration is salinity. In general, lower salinity recycled water is preferred for uses including irrigation on farms and recreation facilities.