Groundwater or surface water
After the groundwater or surface water has been drained from sources in nature, it starts an extensive purification process with both mechanical and biological steps. This becomes our final tap water. Tap water in Belgium complies with strict quality standards; the water is checked for more than sixty different parameters. This is done both by the drinking water companies and by independent laboratories. This makes tap water the most controlled nutrient in Belgium.
A smaller proportion of the drinking water supply in Flanders comes from groundwater. Groundwater is abundant water from rain showers or rivers that infiltrates the soil, where it is retained by rocks and an impenetrable layer that prevents the water from sinking deeper. This then forms a groundwater layer. Because the water seeps between rocks, sand layers or the like, and thus goes through a natural cleaning process, this is also the cleanest water. But because of the years of use of waste products and pesticides that seep into the ground along with the water and overexploitation of the groundwater layers, this source is no longer inexhaustible…
Increasingly, investments are being made in expensive and complex water purification techniques to remove pesticides artificially and faster. Before groundwater is used, studies are carried out to determine which groundwater may or may not be used.
For drinking water production in Flanders, a larger share is drawn from surface water. Surface water comes from rivers, canals, seas… in short, all liquid water forms that can be seen on earth, both natural and artificial. The cleaning of surface water is more intensive than the cleaning of groundwater. Depending on the origin of the water, the quality can vary, in Flanders we are mainly dependent on the Meuse.
From not drinkable to drinkable
The purification process varies according to the source of the water. With groundwater, the water is pumped up, after which oxygen is added to the water. This process causes the dirt present in the water to stick together in flakes. In the next step, the pre-filter process, the water goes through a sand, gravel or carbon filter where the flakes are filtered out. The water is aerated by letting it flow down through a waterfall system, in this step the lime scale is also removed. If necessary, an after-filter is added.
As already mentioned, the purification process of surface water is somewhat more difficult. The first step to get untreated water into our pipes is pumping the water to treatment plants, where it is stored in basins. There it first goes through a mechanical purification. In the mechanical purification, the largest waste particles in the water are filtered out.
Then the water goes through a fine grid, where the largest waste is retained. Sometimes the water also passes through a grease and sand trap, where the grease is scraped from the surface and the sand sinks to the bottom. The water is sieved in different ways. By spraying the water over pebbles once more, the last dirty particles are left behind.
The remaining pollution is eliminated by biological purification. The water is mixed with all kinds of bacteria and microorganisms in a layer of silt and stirred with oxygen. This mimics the natural purification process in which the organisms are broken down into carbon dioxide (CO2), nitrogen gas (N2) and water (H2O). After this process, the water is stored until the sludge has subsided.
After purification, the water goes through quality control one last time, before it flows through our pipes. So we can enjoy fresh, clean water all year round!