Rehabilitation of the Appital potable water tank


A drinking water tank of the Appital seawater desalination plant in Switzerland required rehabilitation. The client set high expectations of both the sustainable quality of the repairs and the future visual appearance of the structure – terms of reference to which the new Type-1 potable water mortar MC-RIM PW 111 from MC was ideally suited.

The Appital seawater desalination plant in Switzerland is located in Au-Wädenswil on Lake Zurich, about 20 kilometres south of the city of Zurich. It was commissioned in 1977 and has since produced around 60 million cubic metres of potable water. But time had taken its toll on a drinking water tank belonging to the plant such that it now required extensive rehabilitation..

Problems of soft water

The company Frei + Krauer AG, Rapperswil, which was entrusted with the planning, commissioned De Lucia Bautenschutz und Renovationen AG of Wädenswil to carry out the repairs. Since one of the reasons for the rehab is the particularly soft water in the region and its corrosive action on the concrete and reinforcement, the new mineral linings needed to offer permanent resistance to such media, which meant a Type-1 mortar had to be used.

MC’s new Type-1 mortar ticks all boxes

Due to the challenge posed by the soft water on the one hand and the planner's as well as the processor's extremely good, long-standing experience with the MC-RIM PW family on the other, they resorted to MC's Type 1 drinking water mortar MC-RIM PW 111, which was introduced in mid-2022 and was developed for the surface protection of wall and ceiling surfaces in drinking water tanks. From a hygienic point of view, the Type 1 classification of mineral coatings sets the highest requirements, as it excludes any additives and plastic-containing additives, something that both the planner and the drinking water operator attach particular importance to. This purely mineral mortar is also impermeable to water, chloride-proof and impresses with its very low porosity. MC-RIM PW 111 thus offers a high resistance to hydrolysis. It even performs better than required by the DVGW (Deutscher Verein des Gas- und Wasserfaches e. V.).

Rehabilitation work on a drinking water tank at the Appital lake waterworks in Switzerland
Rehabilitation work on a drinking water tank at the Appital lake waterworks in Switzerland
© MC-Bauchemie 2023

MC-RIM for system safety

MC-RIM PW 111 was used for the wall and ceiling areas, while the proven mineral high-performance coating MC-RIM PW 301 was used for the floor surfaces and as a bonding agent. Both are based on the DySC® technology (Dynamic SynCrystallisation) developed by MC, which in-creases the impermeability and resistance of the coating during use, thus building up optimum long-term protection.


The refurbishment at the Appital lake waterworks was carried out entirely according to plan between 7 November and 15 December 2022 and was not only able to meet the high expectations of the planners - the processor, who was able to hand over the refurbished drinking water tank on time, was also highly satisfied with the properties of the new hand- and wet-sprayable MC-RIM PW 111.




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