Investments in the drinking water supply involved especially the enlargement of huge water supply systems and the modernization of their facilities. It was necessary to build reliable surface sources and related distribution systems to ensure quality drinking water supply, because the regions of Karlovy Vary and Tachov don´t have enough underground sources. The foundations of these systems were laid in the second half of the 20th century. Since the 1990s, five big water supply systems have been progressively built to replace local unreliable sources. The total length of the five biggest systems today is 1,110 km. They supply drinking water to 90 % of the population in the area of operation and they are still being extended.

The solidarity of municipalities and their cooperation with specialists from the operating company also works in the sewage collection and disposal part. Once again, it permitted to build huge sewer systems with a central sewage treatment plant serving several municipalities, which appeared to be the optimal financial and technical solution. Today about 70% of municipalities in the area of operation have a sewer system finished by a central STP, i.e. about 95% of the population. These are not only all municipalities with the population of 2,000 inhabitants and more, but also the majority of municipalities with the population of over 500 inhabitants. Investments in the modernization or construction of sewage treatment plants and in the enlargement of sewer systems still continue.

Examples of investments in the past:

WTP Svobodka - ultrafiltration unit installation, 2017 - 2020, total costs 1 million EUR

WTP Březová - reconstruction, ultrafiltration unit installation, 2011 - 2016, total costs EUR 1,7 million, first UF implementaiton in CZ.

STP Karlovy Vary - sludge treatment enlargement, law temperature sludge dryer installation, 2015 - 2016, EUR 1,9 million, first implementation in CZ.

Tachov, Stříbro, Chodová Planá – Reconstruction of STP and completing of sewerage networks, 2009 - 2012, total costs CZK 140 million, co-financed by Ministry of Agriculture and the Region of Plzeň

Karlovy Vary – regional water project, 2005 - 2007, Euro 10.63 million, co-financed by the EU Cohesion Fund (64% of total costs) and by the Czech Government
The project included six investments:
Karlovy Vary – reconstruction of STP and town sewerage network
Ostrov – STP modernization
Horní Slavkov – new STP
Jáchymov, Nová Role and Chodov – reconstruction and completing of sewerage networks

Water pipeline to H. Slavkov (2005, CZK 30 million, subsidy Minstry of Agriculture)

Bezdružice and Konst. Lázně region – drinking water supply (2004, CZK 51.5 million)

Ekological networks in Pernink, H. Blatná and Nové Hamry  (2004, CZK 131 million, subsidy EU Phare)

Reconstruction of the STP Karlovy Vary (2003, CZK 106.8 million)

Supplying the Ostrov region with drinking water (2000, CZK 150 million, subsidy Ministry od Agriculture)

Bečov – sewerage network and STP (2000, CZK 28.5 million)