But not for long. Rand Water, where Mosai works as the chief operations officer, has informed the region's municipalities it will reduce water supplies. Water-shedding and water throttling will follow.
"We just don't have an appreciation for water," says Mosai. "It's a problem that we need to wake up to. We're talking about 300 litres per person per day in Gauteng. The world average is 170 litres. The World Health Organisation says you can go to 25 litres for cooking, bathing and flushing. Drinking water is being used to fill swimming pools and gardens."
Rand Water has run water-savings campaigns since 2014. "But it just didn't go anywhere... For the Vaal system to recover we need three years, and even if we have good rainfall for the whole of December, it's not enough.
Mosai called municipal water utilities to a meeting this week to discuss water leaks. "Joburg Water told us they fixed 88 percent of leaks in September in time I don't know how they've done it, but Mogale City has done well with these water restrictions, stopping sprinkler systems in their area."
Dr Chris Herold, president of the SA Institution of Civil Engineering, believes reducing Rand Water's supply at source is the only way to attain the water restriction target fast enough.
"The delay in promulgating and then implementing the 15 percent water restrictions on municipal demand for the first four months of the water planning year means that we have lost 81 million cubic metres of water that cannot be replaced before the current drought is broken, except by imposing even more stringent water restrictions. Hence, to balance the books, we would need to attain a 22.5 percent reduction during the remaining eight months of the year."
He blames decades of municipal failure to curtail water leaks and implement other water demand management measures and the "shocking failure" of the Department of Water and Sanitation to maintain and refurbish the critically important pumps required to transfer water from the Tugela River to Sterkfontein Dam and from the Usutu River to Heyshope Dam.
"Self-preservation dictates that we have to get the water restrictions working quickly by whatever means possible. A little inconvenience now is nothing compared with the tears that will be shed in future if taps run dry for months or even years."
The drought and the growing water deficit in the Vaal river system were not unforeseen, believes Mariette Liefferink, of the Federation for a Sustainable Environment.
"The department's reconciliation strategies for the Vaal river system showed for years a growing deficit and recommended acid mine drainage be desalinated by 2014/2015 and that the Lesotho Highlight Water Project Phase II be constructed by 2020 to mitigate the growing deficit. The Lesotho Highlands Water Project Phase II will now be implemented only by 2025."