Where does your water come from?
The water produced by the SWDE mainly originates from groundwater. The water drawn from quarries and dam reservoirs is also exploited in order to supply the population.
The majority of the water produced by the SWDE originates from groundwater abstraction. Moreover it constitutes one of the assets of the Walloon subsurface, which is particularly favourable for its formation.
The groundwater originates from the seepage of rainwater into the soil. The rainwater percolates by gravity into the pores, micro-cracks and larger cracks of rocks, moistening increasingly deeper layers, until it reaches an impermeable layer. It accumulates there, filling even the smallest gaps, saturating the subsoil with moisture, thereby forming an underground water reservoir called an aquifer. The aquifer advances in the subsoil on the impermeable layer, following slopes, sometimes for tens or even hundreds of kilometres, before coming out into the open air and supplying a source or body of water.
By seeping into the soil, the water goes through several layers of soil and rock that naturally remove its impurities, except for certain pollutants such as nitrate, pesticides and hydrocarbons.
The surface water drawn by the SWDE mainly originates from Wallonia's four large dam reservoirs: the Gileppe dam (in Verviers), the Vesdre dam (in Eupen), the Nisramont dam (in Nadrin) and the Ry de Rome dam (in Couvin).
In order to limit the quantities drawn from vulnerable groundwater sources, mainly in Hainaut, the SWDE has begun to exploit the pit water (resurgent groundwater) from several quarries in Hennuyères. This exploitation of new resources is aimed at reducing abstraction through the rational use of the available potential.
Mostly groundwater or surface water?
The water produced and distributed by the SWDE mainly originates from groundwater (75 to 80%). The remainder of the production is drawn from surface water. It is exposed to pollution of natural and human origin. It therefore requires various fairly complex treatments in order to make it drinkable. This is the function of the treatment plants , attached to the four dams or closely located sites for the abstraction of quarry water.