The filter material must be used for alkaline filtering of drinking water. The objective of the filtering is to separate particular materials, increasing the water alkaline, the calcium level and the pH value. The raw water shall be added carbon dioxide with an amount of 15-25 mg/l. However the contracting authority aims at using as little as possible for achieving the desired water quality.

The filter material must be used for alkaline filtering of drinking water. The objective of the filtering is to separate particular materials, increasing the water alkaline, the calcium level and the pH value. The raw water shall be added carbon dioxide with an amount of 15-25 mg/l. However the contracting authority aims at using as little as possible for achieving the desired water quality.