Lahti Aqua

Lahti Aqua Ltd has long traditions in water services. Lahti Aqua is owned by the city of Lahti and our offices are situated in the harbour.

At glance

  • founded 1910
  • serves 145.000 customers
  • serves in cities of Lahti and Hollola
  • net sales 41,0 M€ (2019)
  • 84 employees
  • 24.000 m3 drinking water produced daily
  • 36.000 m3 waste water processed daily

Lahti Aqua produces drinking water and wastewater services for the cities of Lahti and Hollola. We employ nearly 90 people and our net sales was 41,0 million Euros (2019). We are proud to provide our customers reliable, high quality services and do it sustainably with respect to the environment.

Lahti Aqua Group is divided into four parts. Lahti Aqua Ltd is the parent company for subsidiaries Aqua Service Ltd, Aqua Network Ltd and Labio Ltd. Lahti Aqua is in charge of administration, customer service, planning and development of water services. Aqua Service is responsible for clean water supply and wastewater treatment, and maintenance of the facilities and distribution network. Aqua Network owns the distribution network and facilities and is in charge of investments. Labio produces biogas from wastewater sludge and biodegradable waste.

Drinking water

Lahti Aqua provides drinking water for 145 000 customers in Lahti and Hollola. Almost 24 000 m³ of water is pumped daily for domestic and industrial use.

We use groundwater which is famous for its good quality. Our company makes sure this valuable asset gets the treatment it deserves. Formed in the ridges of Salpausselkä, the groundwater would be drinkable as such. It doesn’t need any purification, but to prevent growth of bacteria in the distribution network, water is disinfected with chloramine and UV light. Sodium hydroxide is used to raise the pH level to prevent corrosion in the network.

Most of the groundwater resources are located underneath residential and industrial areas. Therefore it is vital for us to be active in protecting these resources.


There are three wastewater treatment plants in Lahti which process an average of 36 000 m³ of municipal and industrial wastewater each day. Wastewater is treated mechanically, biologically and chemically to meet the high standards set by environmental authorities. Organic matter and nitrogen are removed by biological treatment and phosphorus is chemically precipitated. Nitrogen and phosphorus are the main nutrients causing eutrophication in lakes and seas. Before discharging into the river Porvoonjoki the treated effluent flows through UV light treatment to remove pathogens. The condition of the river is carefully monitored.