Desalination & Reuse Handbook - Flipbook - Page 10
IDA
WATER SECURITY
HANDBOOK
The Year in Scarcity
CAPE TOWN
In October 2017, following three years of low rainfall – including two record-breaking, century droughts – the City of Cape
Town announced that ‘Day Zero’ was projected to arrive on 12th April 2018. At this point, projected water supplies would be
so low that distribution networks would be cut off, with a per-capita water allowance of 25 L/d available from distribution
points across the city. The projections, based on worst-case business-as-usual scenarios, spurred a step change in how
suppliers and consumers managed their water resources. After weathering the drought without reaching Day Zero, and
being granted slightly more room to manoeuvre after 2018’s winter rains, Cape Town is now looking to consolidate the
gains made by demand management and develop water sources to move away from reliance on variable rainfall.
Despite attention initially given to emergency desalination projects, demand management was the key to averting the
water crisis. Total demand fell from a high of 900,000 m3/d in February 2017 to around 500,000 m3/d through the
winter of 2018, and summer spikes in consumption had been mostly eliminated by 2017. The majority of this was down
to reductions in domestic use, which made up around 70% of Cape Town’s consumption that year. Public awareness
campaigns, water restrictions, and steep tariff increases for higher-volume users were the key drivers of this reduction,
as was the elimination of the free first block of water for most users in 2017. Level 6b restrictions in effect from February
to October 2018 required per-capita water use to drop to 50 L/d. As of April 2018, around 20,000 households had water
usage above 20 m3/month, around 10% of the figure for December 2016.
Day Zero prediction timeline: In October 2017, the City of Cape Town’s media office published a projection that if
business-as-usual continuted, the city would run out of water in April 2018. Known as ‘Day Zero’ – the day when Cape Town’s
taps would be turned off as reservoir levels dropped below 13.5% – was adjusted in real time as reservoir levels fluctuated.
Finally, as the agricultural season ended and dam levels remained 23%, ‘Day Zero’ was pushed back to 2019 pending winter
rains.
October 2018: Level 5 Water
Restrictions to be introduced
target: 500 million L/d
(having never achieved level 6B levels)
1st February 2018
Level 6B Water Restrictions introduced
target: 450 million L/d
69.1%
36.2%
35.1%
26.3%
24.4%
23.0%
Dam levels at time
of prediction %
Sep
DAY
ZERO
DAY
ZERO
DAY
ZERO
Apr ‘18
May ‘18
Apr ‘18
Oct
Nov
2017
2
Dec
DAY
ZERO
Jan
DAY
ZERO
DAY
ZERO
DAY
ZERO
DAY
ZERO
DAY
ZERO
May ‘18 Jul ‘18
2019
2019
2019
2019
Feb
Mar
Apr
May
2018
Jun
Jul
Aug
Sep
Oct
Source: City of Cape Town
