Day Zero dates determined by the rain

The City of Cape Town has announced no further push-backs of Day Zero since the dreaded date was moved to Monday July 9 last month.

In a release issued last week, the City said that if consumption stayed below 450 millions litres a day (MLD), then any new Day Zero projections would depend entirely on how much rain fell in winter.

There are three projections based on rainfall: one at zero rain, one at the same amount of rain as 2017 and the last at 85% less rain than last year.

The current July 9 date, the City said, was the worst-case scenario projection and what might happen if there was no rain this winter.

If the rainfall matches that of last year, then Day Zero is projected for winter next year. If the rainfall is less than last year, Day Zero is projected for February 2019. All of the projections work on the assumption that consumption remains below 450MLD and the augmentation plans run according to schedule.

Last week, consumption averaged at 516 MLD. Dam levels dropped by 0.4% to 24%. The augmentation plans include getting 150MLD from groundwater; 16MLD from temporary desalination; 10MLD from water re-use and 4MLD from springs.

“The City’s three small-scale emergency desalination plants will add approximately 16MLD into the system by May 2018,” the release said.

The plants were being built in two phases, the City said, with a projected yield of:

2MLD within the next few weeks from the Strandfontein plant and 7MLD by May, when it is expected to be at full capacity.

2MLD by mid-April from the Monwabisi plant and the full-capacity 7MLD by mid-May.

2MLD by late March from the Waterfront plant.

The projected yield from ground water sources are:

83MLD from the Cape Flats aquifer by June.

50MLD from the Table Mountain Group aquifers by June; and

The Atlantis aquifer is already producing 12MLD and another 20MLD is expected by

“The temporary 10 MLD re-use plant at Zandvliet is on track to begin full production in June 2018,” the release said.

The projected yields from springs are 3MLD at Albion Newlands and about 2MLD at Oranjezicht.