On 1 January 2016, previous water restrictions of Level 1 from 2005 had been lifted to Level 2 by the City and on 1 November 2016 it elevated these to Level 3, when the Department of Water and Sanitation gazetted water restrictions for urban and agricultural use.
Significant droughts in other parts of South Africa ended in August 2016 when heavy rain and flooding occurred in the interior of the country, The City increased water restrictions to Level 3B on 1 February 2017 and by the end of the dry season in May 2017, the drought was declared the City's worst in a century, with storage in dams being less than 10 percent of their usable capacity.
With the dry summer season approaching, the City increased its existing water restrictions to Level 4B on 1 July 2017, and to Level 5 on 3 September 2017, banning outdoor and non-essential use of water, encouraging the use of grey water for toilet flushing, and aiming to limit the overall per person water usage to 87 litres per day, for a total consumption of 500 million litres per day.
In the same month, the City of Cape Town issued an emergency water plan to be rolled-out in multiple phases depending on the severity of the water shortage.
The immediate cause of the water crisis was the extreme drought from 2015-2017 that exceeded the planning norms of the Department of Water and Sanitation.
Research on long-term weather data done by the Climate System Analysis Group at the University of Cape Town determined that the low rainfall between the years 20 was a very rare and extreme event.
The Cape Town water crisis in South Africa was a period of severe water shortage in the Western Cape region, most notably affecting the City of Cape Town.
While dam water levels had been declining since 2015, the Cape Town water crisis peaked during mid-2017 to mid-2018 where water levels hovered between 15 to 30 per cent of total dam capacity.
Phase 1 compromising "water rationing through extreme pressure reduction" was implemented immediately.
In Phase 2, post "Day Zero", water would have been shut off to most of the system except to places of key water access.