Rainwater harvesting

Water security: A call to action

South Australia is a very dry landscape. Indeed, the South Australian Department of the Environment and Water (DEW) reminds us:

Water is fundamental to our lives. It supports agriculture, beverage and food production, industries like mining, energy and construction, essential services such as our schools and hospitals, right through to providing water for wetlands and sports grounds we enjoy.

In the driest state on the driest inhabited continent, we all have a role to play in managing water sustainably, now and into the future.
Water | Department of Environment and Water (DEW)

This is a call to action for all South Australians to reduce their need on precious water resources, particularly in times of drought.

Historical perspective

South Australian cities are a large suburban sprawl of mainly single storey homes dominating the housing stock. Historically, South Australians practiced rain water harvesting for their drinking water and gardening because of the poor quality of mains water. This changed in the 1990s with improvements to the treatment of mains water.

The Millennial Drought

South Australia has suffered from droughts since European settlement, the most recent being the Millennial Drought which affected most of populated Australia:

The Millennium Drought, from 2001 to 2009, devastated communities, industries and the environment, which all rely on a healthy River Murray to prosper.

A combination of low rainfall and the lowest inflows into the river in recorded history meant flows over the border into South Australia virtually ceased, with unprecedented impacts.
Millennial Drought | DEW

As a result of the millennial drought, governments at all levels were keen to look at ways to reduce our consumption of water in the home. Water capture (rainwater harvesting) can be achieved with some simple techniques:

On an individual site or allotment local capture of rainfall includes the capture of roof runoff in rain water tanks, the use of porous paving or infiltration trenches. Water collected in rain water tanks can be plumbed in to the house to provide an additional water source for a household.
Stormwater | DEW

Government of South Australia initiatives

The Government of South Australia, through the authority of the DEW, is responsible for ensuring that water security measures are made part of current legislation and related policies. The Department of Health and Wellbeing (SAHealth) also plays a role in ensuring that there is regulation in place to protect safe drinking water. Both departments have been active in providing funding for initiatives such as public education and the development of standards for rainwater harvesting.

The Commonwealth Government developed a user guide for rainwater harvesting in 2011: Guidance on the user of rainwater tanks, which SAHealth references on its website. This publication addresses the health concerns of using water harvested from roofs and provides information about how to carry out the calculations for both domestic use as well as the harvesting potential of a residential roof.

Water sensitive SA

One of the initiatives by DEW, SAHealth and urban councils has been to set up a programme to allow professionals involved in urban development to share information and develop methods and technologies for water sensitive urban design (WSUD).

Water Sensitive SA is a capacity building program that provides stakeholders across all disciplines within the development and urban water management industries, with the support they need to achieve the best water sensitive urban design (WSUD) outcomes.
Water Sensitive SA

Water Sensitive SA has some specific web pages and user publications which provide design and installation guidance:

Technical manual for water sensitive urban design in Greater Adelaide. The Government of South Australia produced this comprehensive technical manual in 2010 which is now located in the Water Sensitive SA website. It provides information and examples of how to create elements which fit into water sensitive urban design (WSUD). See Chapter 5 for rainwater tanks.
Rainwater tanks for your home & backyard. This web page contains information about how to size rainwater tanks for local rainfall and house roof diameter. It lists a number of rainwater tank size selection charts, which are location specific such as the one for Mount Compass: Rainwater selection table for Mount Compass.
Rainwater Tank Design and Installation Handbook. This 111 page PDF published in 2008 is the design and installation standard for the rainwater harvesting professionals is produced by Master Plumbers & Mechanical Services Association of Australia (MPMSAA).

Rainwater Harvesting Australia

Rainwater harvesting Australia is a not-for-profit organisation supported by businesses which produce products and services for rainwater harvesting which is a subdivision of Irrigation Australia. Their website contains the Rain Harvesting Residential Design Specification. This publication developed by the Master Plumbers & Mechanical Services Association of Australia (MPMSAA) 2008 is the design specification referenced by Irrigation Australia.

Trade Secrets (presenter: John Caley)

In 2010, John Caley presented a series of four 5 minute videos on how to scope and build a domestic rainwater harvesting system. This presentation series is located on the Trade Secrets Youtube channel.

Part 1: Rainwater systems

This is an overview of the video series which includes the discussion of collection, storage and supply of water within the rainwater harvesting system. Refer to the Rain Harvesting Residential Design Specification discussed earlier for more details related to discussion points in this video series.

Part 2: Collection

This video discusses the suitability of roofs to be used for rainwater collection as well as environmental pollution which may determine how you can use water collected. Gutters and downpipes must be installed with suitable gutter drainage and care needs to be taken to avoid the buildup of leaf debris. First flush diverters can protect the water supply from accumulated dirt or debris which can build up on the roof between rainfalls. Rainwater systems located in climates where there is variations in rainfall from one part of the year to another need to have first flush diverters which can be drained.

Part 3: Storage

This video discusses the types of tanks including above ground tanks, using multiple tanks as well as in-ground tanks. The volume of water stored is dependent on space availability within your property to place tanks, how the rainfall will be used on your property, the roof area available to harvest rainwater, and the rainfall pattern of your local area. Attention needs to be paid to keep control of mosquitoes and the handling of tank overflows.

Part 4: Supply

This video discusses the type of pumps available to suit the supply demands of usage. There are pumps and related devices which are suitable for a range of applications including devices which allow the use of both tanks and mains water when rainwater is not available. For household use, rainwater systems must be fitted with protection from back flow of contaminated water into the drinking water supply. It is also important to have filters in place to further protect water quality. Users should be supplied with information to ensure good maintenance of the rainwater system.