South Africa - recycled water for toilet flushing ...

Excerpt from Cape Times:

SA consider other water sources to flush loos

10 December 2007

Instead of wasting top-quality drinking water to flush toilets or to water gardens, South Africa is looking at the feasibility of using recycled sewage water, storm water or sea water.

The proposed dual water reticulation scheme is known as the "purple pipe system" in some countries because recycled water pipes are colour-coded in purple or lilac to distinguish them from drinking water pipes.

The colour-coding is intended to ensure that people do not drink the second-grade water supply by accident, and also to reduce the risk of accidental cross-connections during plumbing alterations

The Water Research Commission in Pretoria says the purple option continues to attract interest at high political level - despite findings that suggest recycling and desalination are too expensive.

The cost of altering home plumbing is also seen a major barrier.

But Jay Bhagwan, the commission's director for water use and waste management, says recycling technology has evolved considerably since the studies in the late 1960s.

Because South Africa is likely to face significant water shortages in the near future, the commission has decided to revisit purple pipe options.

Experts from the Universities of Johannesburg and Witwatersrand are to complete a feasibility study in March.

Bhagwan said parts of Hong Kong had been using a dual system for several years. Toilets were being flushed with sea water and Hong Kong authorities were thinking of extending the system to other parts of the district, using recycled sewage water instead of salt water.

Some Australian cities have installed the purple pipe system in new residential areas. In one such development, Rouse Hill, north of Sydney, demand for drinking water is said to be on average 40 percent lower than in older areas.

Because of critical water shortages, the Namibian capital, Windhoek, began to recycle sewage water for irrigation in 1968 and nearly 35 percent of its drinking water is from ultra-treated sewage water.

Yet the purple system is not without mishap.

In 2001 in the Netherlands, about 200 people developed gastrointestinal problems after an accidental cross-connection of drinking water with purple water at a housing development.

A similar problem arose in Milnerton in May 2004 involving a primary school that used recycled water to irrigate its sports fields.Investigations after several people developed diarrhoea and vomiting suggested school officials had cross-connected the two systems to remedy low pressure problems in the recycled water pipeline.

See - Recycled water for loos.