Cape Town faces “catastrophic" consequences as water taps to four million citizens will be turned off within the next 80 days.

Unless the skies defy weather forecasts and rain floods the city’s six dams, "Day Zero” is April 12.

This is when the municipality will shut taps and residents will have to queue to collect water daily at about 150 sites around the already congested city.

Many fear lack of water will spark civil unrest and even more crime, as the economy – which is heavily dependent on tourism – shrinks. Many bookings from overseas visitors have already been cancelled for the end of summer season.

Behind closed doors, some in the city’s management are predicting nearly a third of better off residents will lock up their homes and leave ahead of Day Zero.

Jean-Pierre Smith, Cape Town’s safety and security member within the mayor’s office, said the city is unsure how all citizens will be able to collect water when the taps are turned off.