South Africa is bracing for yet another heat wave and the most populous metro is to ration its water supply. Johannesburg, which has 4.4 million residents, has from today implemented level2 restrictions.The situation is set to get worse, with the South African Weather Service predicting below-average amounts of rain until beyond March.Yesterday city officials said if the level of dams dropped, further level3 restrictions might have to be implemented. These entail supplying water only at stipulated times of the day, for example, only in the mornings and in the evenings at times to be announced.To prevent such restrictions, authorities have advised residents to:Use borehole water and bath water, or grey water, for gardens;Take shorter showers;Do not leave water running when brushing teeth; andDo full loads in washing machines and dishwashers.In Cape Town, city officials say restrictions aimed at saving a further 10% of water will be announced soon. The dams supplying the city are "lower than usual".The level2 restrictions in Johannesburg forbid residents from:Watering gardens between 6am and 6pm;Filling swimming pools; andUsing hosepipes to wash cars and paved areas.Rand Water, the biggest water supplier in Gauteng, has warned that if the drought persists, dam levels could drop to as low as 29.7% by January.Weather forecaster Madinetja Thema said yesterday summer rainfall in South Africa was predicted to be well below average until at least March."Short-term weather forecasts are far more accurate than long-term forecasts, which can change on a month-to-month basis," he said, warning that long-term forecasts were not an exact science."What we can say is that we are going to experience very hot weather for quite some to come."Last year, The Times reported, based on a council report, that demand for water in Johannesburg would far outstrip supply by this year unless evasive action was taken.The report noted that Johannesburg had to reduce its water demand to 450billion litres by this year but demand currently stood at 577.3billion litres annually. The city lost 127billion litres of water between August last year and July this year, but, in contrast to that, managed to save 2billion litres last year.Today seems a faraway world from last week when Johannesburg Water merely appealed to residents to use water sparingly while insisting that the city could count on the 630billion-litre Sterkfontein Dam for additional reserves.Now there are no more appeals.Johannesburg official Matshidiso Mfikoe said that Rand Water had yesterday notified the city of further deterioration in the bulk-supply system, recommending a higher level of water restrictions."It is against this backdrop that the City of Johannesburg has to invoke Section 44(3) of the Water Services by-law."The city said it would rely on members of the public to report each other's non-compliance with provisions of restrictions.Additional reporting Aarti J Narsee..