01 · The problem
What is happening
Cape Town depends on surface reservoirs filled by winter rainfall. Three consecutive poor rainfall years drew dam storage down to critical levels, and the city publicised a "Day Zero" at which municipal taps would largely be turned off. Severe restrictions, pressure management, leak repair and an extraordinary demand reduction by residents, together with returning rainfall, avoided that outcome. The episode is widely studied as a case of urban water crisis management, and the city has since diversified supply planning.
High severity. Serious, widespread effects requiring sustained action. Severity is descriptive editorial metadata summarising documented effects. It is not a measured index or a score.
02 · Causes
Why it is happening
- 01
Consecutive low-rainfall years
Three successive poor winter rainfall seasons reduced inflow to the supply dams.
- 02
Surface-water dependence
A supply system built almost entirely on rainfall-fed reservoirs is highly sensitive to rainfall variability.
- 03
Demand growth and distribution losses
Population growth and losses from ageing pipe networks raised baseline demand before the drought.
03 · Impacts
Who and what it affects
- 01
Near shutdown of municipal supply
The city planned for a day when most taps would be closed and residents would collect water from distribution points.
- 02
Economic disruption
Agriculture in the surrounding region faced restrictions and job losses, and tourism messaging was affected.
- 03
Lasting behavioural change
Household water use fell dramatically during the crisis and remained below pre-drought levels afterwards.
04 · Solutions
Documented approaches
Demand management and pressure control
Tariffs, restrictions, leak repair and network pressure management to cut consumption and losses.
Expected effectAchieved a very large, sustained reduction in city water use during the crisis.
Supply diversification
Groundwater schemes, water reuse and desalination to reduce reliance on rainfall alone.
Expected effectLowers the risk that a single dry sequence threatens supply.
Catchment clearing of invasive species
Removing thirsty invasive alien plants from supply catchments to increase runoff into dams.
Expected effectRecovers water at relatively low cost per unit compared with new infrastructure.
05 · Key indicators
What can be measured
- Day Zero
- Announced, not reached2018
The city publicly scheduled a date at which municipal supply would largely be shut off. Demand reduction and returning rainfall meant it was never reached.
- Drought period
- 2015-2018
Three consecutive below-average winter rainfall seasons drove reservoir storage to critical levels.
06 · Sources
Where this comes from
- [1]Water Outlook and drought response reportingCity of Cape Towncapetown.gov.za(opens in a new tab)
- [2]Cape Town drought: lessons for urban water security (publisher site)World Resources Institute · Feb 2018wri.org(opens in a new tab)
Links open the publishing organisation's site. Some point to the publisher's main page, where the named report or dataset can be found.