Johannesburg — ABOUT 30% of household water consumption is used to flush toilets, and SA needs to consider dry sanitation, according to a water and sanitation specialist.

Most toilets use 6l of water per flush, while even more efficient versions can use nearly 5l.

"We can't carry on using 1860s technology and use drinking water to flush away human waste," said Neil Macleod, head of water and sanitation at eThekwini municipality, at a conference for sustainable water use this week in Pretoria.

Better technology for dry toilets are needed, but currently this is not acceptable to consumers. "Poor people want the same technology you have, not 'inferior' technology."

Durban had invested in market research - known as the Pooh Project - on the relationship people have with their toilets. It found that people wanted clean, odour-free, light-filled toilets, but municipalities supplied dark, smelly pit latrines, he said. While water was not mentioned in the responses, the presence of water in toilets represented cleanliness.

Urine-diverting toilets - collecting urine separately from solid waste - could be used to harvest valuable nutrients, such as phosphorus for agriculture. This could generate income of 50-60 per person, Mr Macleod said.

"That might not sound like much, but for a poor person, that's an extra R500 they wouldn't otherwise have." The phosphorus price was expected to increase.

Sustainable sanitation also implied recycling sewage water, which was not socially acceptable, although cities such as Windhoek treat sewage water to drinking water standards.

"It happens all over the world already, but society does not see the connection. Most rivers contain sewage from communities further upstream and that water is consumed without much complaint," Mr Macleod said.

It was more cost-effective to treat sewage water than to desalinate sea water, he said.

Water needed to be priced effectively, he said. Often prices do not recover operating and maintenance costs, let alone capital charges, and this encouraged wasteful consumption.

The replacement cost of water and sewerage assets in Durban was R32bn, "but we provide for depreciation at their historic cost of less than R3bn. This is not sustainable in the longer run."