Flanked on both sides by deserts, Namibia is amongst the most arid countries in the world. Windhoek, its capital is situated in the central highlands with a mean annual precipitation of 370mm, evaporation of over 3,000mm and 750km from the nearest perennial river. For more than five decades Windhoek has managed to stretch its limited potable water resources through strict water management, including wastewater reclamation and direct potable reuse. After years at or near the top of the media agenda, water conservation habits are well ingrained in the minds of the city’s residents. Per capita use is 180 litres/day and unaccounted for water is only 10%. Water supply is based on a combination of limited surface water and groundwater resources and due to their highly uncertain nature, the city council put in place a comprehensive integrated water demand management programme in 1994 to ensure water security for the city. Direct potable water reuse started in 1968 and has been a feature of the city’s water supply ever since. The original scheme was replaced by a new plant in 2002. Operating at 73% of its capacity the new plant provides more than 18,000m3 /day of drinking water. This is 26% of Windhoek’s water demand and is part of a total re-use system in which very little water is either wasted or returned to the river system.
- Multibarrier approach to ensure safe and aesthetically acceptable potable water.
- Guaranteed water quality values.
- Blending of reclaimed water with freshwater.
- 20 year operation and maintenance agreement.
- Public awareness campaigns for water saving and acceptability of direct potable water reuse.
- Project financing: by the KFW (Kreditanstalt fur Wiederaufbau) (40%), the European Investment Bank (55%) and the City of Windhoek (5%).
- Availability of additional 7,500,000m3 /yr of potable water at a similar cost to other sources.
- Availability of reclaimed water from the old plant for the irrigation of parks, sports fields and pasture.
- Deferment of expensive infrastructure to transport water from alternative water sources at a greater distance.
- Continued acceptance by the public of potable water from reclaimed waste water.
- Reinforcement of high levels of water demand management and conservation practices.
- The impact of returned downstream flows on the basin is minimal as there is little downstream water demand.
Taken from the report ‘Managing Water Use in Scarce Environments’ by 2030 Water Resources Group.