Design of a new toilet cistern for the replacement market

Abstract: This thesis was performed at Caroma (Industries Limited), Adelaide,
Australia. Caroma is the leading manufacturers of toilets and bathroom
accessories in Australia. One of their most popular products is the plastic
toilet cistern, a cheaper alternative to the vitreous china cistern. Caromas
plastic cisterns are very common in Australian homes and public bathrooms.
All of their cisterns are manufactured at Caromas manufacturing plant in
Norwood, Adelaide, where they also produce other plastic components such as
valves and toilet seats.

This project will be emphasizing on the styling of a new cistern and its
design and it will consist of a tank, a lid, a connection plate and dual
flush button setup.

The main aim of this thesis is to present the product development and design
of a new plastic cistern intended for the replacement market. The new cistern
shall be big enough to cover the footprint of plastic cistern out on the
market, Caromas own brands and other producers. Caroma has got more then 10
different models of plastic cisterns and they all got different footprints
(the footprint is the wall area that the cistern covers). Some of the models
are up to 30 years old and need to be replaced because of malfunction but
also because of their old-fashioned styling. The old models are often very
big and have got a big footprint. If a cistern has to be replaced the new
cistern shall cover the footprint so that no marks, left by the old cistern,
are visible on the wall and no further renovation is necessary. In order to
optimize the required footprint, plastic cisterns were measured and charted.

The product development started with brainstorming and an ITK, Identity Tool
Kit. The ITK is used to get a general idea about what style was wanted. Three
concepts were generated and presented to Marketing in Sydney. A concept was
chosen by using systematic concept selection and after having had input from
marketing.

The result of the project is a new plastic cistern that covers the required
footprint and has a style that goes well with contemporary bathroom design as
well as with older. It has a slim shape and looks proportional. The cistern
has also got a shelf feature that allows placing objects on top. The button
setup is designed as a rocker and adds a new type of button to the Caroma
product range.

The new cistern design is presented with rendered CAD pictures and a
full-scale prototype. A physical model is from a marketing point of view more
convincing. It gives not only a visual experience but also a tactile.
When designing the new cistern, manufacturability has been taken into
consideration. Knowledge about the processes and manufacturing techniques has
improved the design utilizing the properties instead of consider them as
limitations.

This project will hopefully give Caroma inspiration to start manufacturing a
new plastic cistern design.