Around two billion people rely directly on aquifers for drinking water ⁽¹⁾. These aquifers are naturally recharged with surface water which contains up to 80% treated wastewater under dry weather flow conditions. Internationally it is common practice to artificially recharge aquifers with appropriately treated stormwater and wastewater where it mixes with groundwater which is often cleaner than surface water. The aquifers can then be drawn on to supply water for new uses including drinking water.

Figure 1. Estimated extent of groundwater used for drinking water in Asia and Latin America. © 2003, UNEP, DFID and NERC ⁽¹⁾.

Germany

Berlin, Germany is dependent on groundwater for its potable water supply but annual precipitation of around 600mm/year is not sufficient to replenish aquifers which supply 100% of the potable water which is not chlorinated. Berliner Wasserbetriebe the region’s water and wastewater provider (half owned by a Veolia Water/RWE consortium) have used bank filtration and artificial groundwater recharge to supplement natural recharge (see Figure 2). The mechanisms governing the removal of impurities and chemicals reactions have not been sufficiently understood and hence a larger multi-stakeholder cooperation project was initiated ⁽²⁾.

Berliner Wasserbetriebe treats the 248, 000 m³ of wastewater the company receives each day and uses it to recharge surface water lakes ⁽³⁾. This surface water is used to artificially recharge aquifers through artificial infiltration ponds and bank filtration by means of natural lakes. The groundwater is then abstracted to supply 3.4 million people in Berlin with drinking water without chlorination.  

Figure 2. Aquifer recharge in Berlin

Singapore

The NEWater initiative between Singapore’s Public Utilities Board and Ministry of the Environment began in 1998 with the objective of assessing the appropriateness of treated wastewater as an additional water source. The treated wastewater undergoes microfiltration and reverse osmosis to create NEWater which is supplied directly to industry and to potable water treatment plants as a raw water source via surface water catchment reservoirs.

Reports commissioned by the Public Utilities Board confirmed that NEWater meets the U.S Environmental Protection Agency and World Health Organisation drinking water standards. Since 2002 when NEWater entered potable supply, it has only represented 1% of total daily water consumption (11.4 million litres per day) and even by 2011 is only expected to represent 2.5%; the majority of NEWater is used for non-potable applications ⁽⁴⁾.