Drinking Water Preparation

Main stages in drinking water production:

Water withdrawn from the natural environment will follow these three main processes to become suitable for drinking:

1. Settling:

Coarse and fine screening. The water is filtered first through a screen to catch the biggest particles, then through a fine-mesh sieve to trap smaller ones.

Flocculation and settling. A coagulant (Chemical product) is mixed with the water to cause the remaining waste—dust, dirt particles, etc.—to clump together. These flocculates sink to the bottom of the settling tank. Around 90% of suspended solids (SS) are removed during this operation.

2. Filtration:

The water flows through a filter, fine sand bed and/or active carbon filter. Sand filtration eliminates matter still visible to the naked eye. Active carbon filters trap micro-pollutants such as pesticides. There are even more advanced filtration processes, such as membrane filtration.

3. Disinfection (different processes possible):

Ozonation: the water is disinfected using ozone, which has bactericidal and antiviral properties. Ozone mixed with water also acts on organic matter, breaking it into pieces, and improves the color and taste of water.

Chlorination: chlorine is added as the water leaves the production plant and at various points in the distribution network, to prevent the growth of bacteria and maintain the water’s quality as it makes its way through the networks.

Ultra Violet: UV irradiation can be used for multiple purposes in water treatment, but is primarily employed as a disinfection process that inactivates waterborne pathogens without chemicals.

Source: Veolia and Siemens