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Key departmental publications, e.g. annual reports, budget papers and program guidelines are available in our online archive.

Much of the material listed on these archived web pages has been superseded, or served a particular purpose at a particular time. It may contain references to activities or policies that have no current application. Many archived documents may link to web pages that have moved or no longer exist, or may refer to other documents that are no longer available.

Design for Environment - Caroma Dual Flush

Caroma logo "Culturally, Australians have a deep-rooted appreciation of the need to conserve water and have shown a willingness to accept the introduction into the marketplace of bathroom appliances that are environmentally and socially responsible."
Steve Cummings, Research and Development Manager

Caroma designers and technicians have designed a AAA Water Conservation Rating dual flush toilet system to reduce water usage and provide resulting financial benefits. The combined six litre full flush and 3 litre half flush (6/3 litre) dual flush system is the latest development in Caroma's research and technological advancement. The unit has an average flush volume equivalent to only 3.8 litres, with the potential to reduce a family of four's water usage by up to 67 per cent compared with the traditional 11 litre single flush cistern.

Caroma was founded by Charles Rothauser in 1941. Production and technological innovation began in 1945 with the creation of the world's first transfer injection moulder (an innovative plastic moulding process). With this process the company produced the first plastic hypodermic syringe, then in 1956 the "Deluxe" all-plastic cistern. Today Caroma is regarded as the undisputed leader in the Australasian sanitaryware industry.

Caroma is a wholly owned subsidiary of GWA International Limited, a Brisbane-based, Australian-owned company, with diverse interests, including Sebel Furniture, Rover Mowers, Poolrite, Dux Water Heaters and Gainsborough Hardware. GWA employs more than 3000 people.

Design for environment

Australia is the driest inhabited continent on earth, with over 70 per cent of the land surface comprising desert or semi-desert. Water consumption from bathroom appliances was not considered a major issue in Australia until the 1970s, with the need to address bathroom water usage driven mainly by water authorities and governments.

Caroma began investigation and development of dual flush systems with a Commonwealth Government industry grant (approximately $150,000) in the late 1970s. The company recognised that the technology had the potential to meet economic, market and environmental objectives.

Dual flush comprises a full flush to remove solids and paper, and a reduced flush to remove urine. Systems with this capability were available in the Australian marketplace prior to 1980; however they had very limited public acceptance due mainly to operational complications. Such systems required the user to activate each flush with different operations. The reduced-flush mode was controlled with a normal push-button operation, while the full flush meant holding down the button until the flush cycle finished. If the button wasn't held for long enough, insufficient water was released to properly cleanse the pan.

Two button flush mechanism

The development program for the first dual flush system focused on simplifying operational aspects of the outlet valve mechanism employing two buttons. A fundamental design consideration was that the flush mechanism needed to be simple and straightforward to operate, while appealing to users who, given the choice, would act responsibly to conserve water.

The process

The decision to develop a 6/3 litre system followed a trial to investigate reduced flushing volumes in sewer systems undertaken in partnership with Brisbane City Council. The trial aimed to find the most economical and effective flushing capacity for toilet cisterns and their potential water savings. The investigation concluded that the new market for cisterns and pans should be in the 6/3 dual flush range, as water conservation performance was excellent and it followed the European direction to reduce bathroom water consumption.

The 6/3 litre system technology was developed over seven years leading up to 1993. Conceptual design work was produced initially in prototype form in the laboratory for subsequent validation in live field trials. Design refinements then improved the performance of the cistern and drainage network. The design, test and redesign approach was repeated many times until a satisfactory final design was empirically validated.

In view of the potential water savings offered by the 3 litre half-flush volume, it was imperative that user expectation for the removal of urine and paper was clearly satisfied. User trials were instrumental in the development of a successful design. Regular inspections of trial installations together with householder discussions and questionnaires were used to gain necessary feedback. These were fully addressed at both prototype and final commercial model stages.

Minimising water consumption was not the only environmental factor addressed in the design of the dual flush system. Caroma used a number of DfE strategies to address the entire life cycle of the system.

The dual flush system

The system has been designed for ease of assembly and longevity, with minimal and durable components. The valve mechanism controlling the dual flush contains recycled ABS plastics sourced from Caroma's manufacturing waste. Life cycle testing on the valve has indicated that it has a life span of approximately 30 years. The life span of the complete system (subject to some servicing and replacement of rubbers) should equate to that of the house in which it is installed.

The toilets incorporating the dual flush system have been designed with environmental low-impact materials of either inert plastics or vitreous china.

The plastics are recyclable and the vitreous china has a number of second life applications.

The manufacturing process is continually assessed for efficiency in energy and water consumption and waste outputs (solid, liquid and air). This assessment has been enhanced through the introduction of an ISO 14001 accredited
environmental management system for the company's plastics section.

Issues and barriers

Key design and development issues included:

Failure to properly address any of these issues would have made the water savings benefits and the commercial viability of the 6/3 litre dual flush system unable to be fully realised in the Australian marketplace.


To ensure the optimum performance of its dual flush technology, Caroma has developed a monitoring system to track products from manufacture to installation and repair. This process has been implemented as part of the company's ISO 9001 accredited Quality Management System. A bar code system has been developed for recording product information such as the date and place of manufacture and components installed. This information can be accessed during servicing of the system.

Environmental benefits

Studies conducted in 1993 simulated the estimated projected water savings in Australia, over time, of a 6/3 litre dual flush system compared with other flushing volumes. The study addressed total current population, projected population, total current number of households, projected number of households, number of toilets per household, and flush volumes in current use. The results of the study showed that water consumption from toilet cisterns (litres per person per day) has fallen from 55 litres in 1982 to 18 litres in 1993.

Data from the study clearly showed that, for Australia, the amount of water used for toilet flushing in the year 2020 was anticipated to be less than the amount used in 1991. This result was achieved even with a projected population increase to 26,707,000.

Economic benefits

Caroma International, the export division of Caroma Industries Limited, was established to service the world market. Caroma products, including the 6/3 litre dual flush system, are now shipped to more than 30 countries worldwide.

In Australia, the widespread adoption of this technology has conserved precious fresh water reserves and resulted in decreased costs in the following areas:


Caroma are currently working to reduce water consumption even further. The company now produces 4.5/3 litre dual flush toilets for the Singapore market. These systems have also been used on a limited basis for environmentally sensitive areas (eg wilderness areas) in Australia in conjunction with grey water recycling.

Contact information: Caroma Australia
Phone: 131774
Free fax: 1800 241 199

Caroma Taps Australia
Phone: 131416
Free fax: 1800 818 346

Caroma New Zealand
Phone: (09) 273 5320
Free fax: 0800 423 825

Caroma International
Phone: 61 3 9926 5477
Fax: 61 3 9354 0017

Caroma Internet: http://

Case study prepared in September 2000