Total Watermark - Making Melbourne a Water Catchment

Leading the way in sustainable water management, the City of Melbourne have recently released its new policy which focuses on ways that aim to make Melbourne a more water sensitive city.  The new policy titled Total Watermark City as a Catchment follows on from previous City of Melbourne water management policies that began in 2002 then were supported by the adoption of Total Watermark in 2004 and the Water Sensitive Urban Design (WSUD) Guidelines in 2005.  

According to the document recently published by the City of Melbourne, the new policy revises Total Watermark to place it within the 'city as a catchment' context and aims to protect our waterways, respond to climate change and sustainably manage the total water cycle. Further to this, the new policy recognises and acknowledges that a single centalised water supply is not a sustainable option for a city like Melbourne due to recent changes in the climate that have resulted in reduced rainfall in eastern and southern parts of Australia.

Urban.com.au certainly supports alternative water supply initiatives which aim to passively and actively use our current infrastructure to better manage relatively easily attainable resources such as rainwater and storm water. 

The policy adopts sustainable water management hierarchy incorporating water supply within and beyond the local catchment and is supported by the Model WSUD Guidelines developed by the City of Melbourne in conjunction with the cities of Port Phillip, Stonnington and Yarra.  According to the policy document, the management considerations are as follows:

• Reduce water demand to conserve water and minimise the generation of wastewater, across all new building and infrastructure works as well as refurbishments and extensions.
• Consider rainwater harvesting as a simple and low impact alternative water source requiring little, if any treatment.
• Consider stormwater harvesting providing the dual benefits of water savings, and improving water quality (by preventing polluted water going down the drain).
• Consider water recycling with a focus on low-energy, low maintenance systems.

The policy document goes further by emphasising the considerations of rainwater and storm water beyond the local catchment by stating the City of Melbourne must account for the following:

• Consider wastewater carried along the Melbourne Water Sewerage Transfer Network. Use low energy technology, and ensure that demand is great enough to maximise the system.
• Consider storm water in the Yarra River, Maribyrnong River and Moonee Ponds creek. At the 'bottom of the catchment' the City of Melbourne is not generally limited by environmental flow requirement, but it is necessary to assess other environmental factors.
• Consider potable water use from the centralised mains system if none of the above water management approaches are suitable for a particular site.
• Consider groundwater. This is a low priority for the City of Melbourne as the groundwater within the municipality is shallow and saline.

Now that the playing field has been set, the City of Melbourne has also set out performance targets to help measure the success of the policy implications in response to the aforementioned considerations. In essence the policy commits the City of Melbourne to increasing water sourced from alternative supplies, improving stormwater quality, reducing wastewater and supporting groundwater.  These targets are as follows:

Water saving targets

• 50 per cent reduction in potable water consumption per employee by 2020.
• 40 per cent reduction in potable water consumption per resident by 2020.
• 90 per cent reduction in potable water consumption by Council by 2020.
• 25 per cent 'absolute' water saving target by 2020.

Alternative water use targets

• Council will source 30 per cent of its water needs from alternative water sources by 2020.
• Non-Council land managers will source nine per cent of their water needs from alternative water sources by 2020.

Storm water quality targets

• ​20 per cent reduction in total suspended solids (soil, tyre residue etc.) on Council and non-Council land by 2020.
• 30 per cent reduction in litter on Council and non-Council land by 2020.
• 15 per cent in total phosphorus (fertilisers, detergents etc.) on Council land by 2020.
• 25 per cent in total phosphorus (fertilisers, detergents etc.) on non-Council land by 2020.
• 30 per cent in total nitrogen (fertilisers, air-borne pollutants etc.) on Council land by 2020.
• 40 per cent in total nitrogen (fertilisers, air-borne pollutants etc.) on non-Council land by 2020.

Wastewater reduction target

• 30 per cent reduction in wastewater across the municipality by 2020.

Groundwater quality target

• Where groundwater needs to be re-injected to prevent land subsidence, it needs to be of equal or better water to the water in the aquifer.

Clearly, these are quite ambitious performance targets that the City of Melbourne has set itself, however Urban.com.au will always support sustainability policies such as this where governing bodies set an example to others.

Recently, Urban.com.au highlighted one particular project known as the Darling Street Project located in East Melbourne which captured storm water run-off then filtered the water using a biofilter before re-using the water to look after the water demands of the nearby Darling Gardens.  This project is certainly in-line with the Council's Total Watermark policy and shines a spotlight on the need to conserve a valuable resource and to constantly think of new ways to capture and re-use water that usually runs into the drain.  

It is also important to point out that due to the success of the Darling Street Project, the Council is funding a new project located in the Fitzroy Gardens which is essentially the same as Darling Street however on a much larger scale, which is very encouraging the see and shows the Council is practicing what it is preaching.

Some future challenges that lie beyond the targets within the municipality will be implementing a similar policy across metropolitan Melbourne Councils. When you consider Melbourne's ever increasing population growth and planning policy shifts toward higher density living, water quality and supply pressures around the current water systems will increase, so in hindsight implementing a similar policy may not be too challenging after all as Councils may not have a choice.

Further reading on the Total Watermark - City as a Catchment policy document can be sourced here.