The journey of clean water to your tap
We clean the natural water thoroughly at the water treatment plant to turn it into the high-quality drinking water that comes out of your tap. For the water, this is a journey that takes a total of 17 hours. After that, the drinking water is pumped into the pipes and delivered to every home in the city.
The journey of clean water to your tap
We clean the natural water thoroughly at the water treatment plant to turn it into the high-quality drinking water that comes out of your tap. For the water, this is a journey that takes a total of 17 hours. After that, the drinking water is pumped into the pipes and delivered to every home in the city.
Water's journey back to nature
The Paljassaare Wastewater Treatment Plant receives wastewater and stormwater from almost half a million people in Tallinn and its surrounding area. Every year, we thoroughly treat more than 50 million cubic metres of wastewater and stormwater to protect the environment and the Baltic Sea.
The journey of clean water to your tap
We clean the natural water thoroughly at the water treatment plant to turn it into the high-quality drinking water that comes out of your tap. For the water, this is a journey that takes a total of 17 hours. After that, the drinking water is pumped into the pipes and delivered to every home in the city.
Renewable water resources
Tallinn's main source of drinking water is renewable surface water, and almost 90% of consumers in our service area get their drinking water from Lake Ülemiste.
If necessary, the additional water resources of the Soodla and Paunküla reservoirs can be used to increase the capacity of Lake Ülemiste, thus ensuring a year-round supply of drinking water.
The lake water is drawn into the water treatment plant, where the multi-stage treatment process begins.
About 10% of Tallinners get their drinking water from groundwater wells. We also treat the groundwater to ensure it is always clean and fresh.
Ülemiste Water Treatment Plant
First, the lake water undergoes mechanical treatment. The screens remove reeds, algae and other large debris from the water.
Microfilters, which are rotating drums covered with fine fabric, trap natural plankton.
Ülemiste Water Treatment Plant
Next, ozone is injected into the water to destroy pathogens and harmful micro-organisms. Ozonation also helps to improve water transparency.
To produce ozone, we feed the prepared air into tubes inside ozone generators. There, the electrical voltage and air combine to produce an independent gas that forms ozone.
The ozone is fed into contact basins where it is turned into tiny bubbles to mix with the water as efficiently as possible.
The ozone is collected immediately from the water's surface and routed to a destructor to prevent it leaking into the production area or the environment.
Ülemiste Water Treatment Plant
After ozonation, the water is disinfected, but it still contains dissolved particles that do not settle on their own. Chemicals such as coagulants and flocculants are used to promote settling.
Coagulants make the particles in the water larger. Flocculants make them stick together.
The water is fed into the clarifier from the bottom up, and the particles become trapped in the floating layer. The water that has passed through the layer is then sent to the rapid filters.
The collected particles are discharged into a lower chamber of the clarifier called the sludge sump. The sludge sinks to the bottom and is then washed to the sewer.
Ülemiste Water Treatment Plant
Rapid filters use a variety of materials, such as gravel, sand and anthracite, to trap the last tiny particles.
Ülemiste Water Treatment Plant
After the filters, the clean water moves to the reservoirs. A small amount of chlorine is also added along the way.
Chlorine helps to maintain water quality in the pipes and keeps water fresh until it reaches the consumer.
The amount of residual chlorine in drinking water is strictly regulated and can be up to 0.5 mg/l at the consumer’s tap.
Water pumping stations
The public water supply system has 22 water pumping stations and 49 groundwater pumping stations that help to take water through pipes to homes and businesses.
The pumping stations ensure sufficient water pressure, helping to deliver water to areas far from the Ülemiste Water Treatment Plant, as well as to the higher floors of buildings.
Water pipes
There are more than 1,200 kilometres of water pipes in Tallinn and its surrounding area, supplying clean drinking water to all consumers in our service area.
Each year, we rehabilitate and construct water pipes as needed to minimise the number of customers affected by service interruptions and to ensure a smooth, high-quality water supply.
Samples of tap water taken daily from customers' taps confirm that it is of excellent quality
Water's journey back to nature
The Paljassaare Wastewater Treatment Plant receives wastewater and stormwater from almost half a million people in Tallinn and its surrounding area. Every year, we thoroughly treat more than 50 million cubic metres of wastewater and stormwater to protect the environment and the Baltic Sea.
Wastewater and stormwater pipes
The sewers collect wastewater and stormwater, and transport it away to prevent its release into nature or a living environment.
The older districts of Tallinn, such as the City Centre and North Tallinn, predominantly have combined sewers, in which stormwater and wastewater share the same pipe. Newer parts of the city have separate sewer systems where stormwater and wastewater are separated.
We are developing Tallinn's stormwater system to keep pace with changing climate conditions. In addition to stormwater pipes, we are building nature-based and combined systems.
Wastewater pumping stations
The public sewerage system has 181 wastewater and stormwater pumping stations.
The pumping stations help to prevent flooding and sewage backflow, and ensure that wastewater reaches the treatment plant without harming the environment.
The main pumping station, which collects all the wastewater and stormwater from Tallinn and its surrounding area, is located in Paljassaare. Here at the main pumping station, the water passes through the primary screens and is then pumped to the treatment plant.
Mechanical treatment
The aim of mechanical treatment is to remove the trash, grit, oils and fats that rise to the surface of the wastewater, as well as the larger particles that sink to the bottom.
Mechanical treatment stage consists of screens, grit traps and primary clarifiers.
Every year, we remove more than 730 tonnes of trash and 200 tonnes of grit from the wastewater.
Aeration tanks
The biological treatment is carried out in aeration tanks using an activated sludge process.
Activated sludge is made up of millions of bacteria that need the nutrients found in wastewater, such as nitrogen and phosphorus, to survive.
Under the right conditions, the bacteria eat up any excess dissolved pollution in the wastewater and multiply.
Secondary clarifiers
The wastewater still containing activated sludge is then sent to the secondary clarifiers. There, the activated sludge is separated so that it does not return to the environment.
Part of the activated sludge is pumped back into the aeration tanks and part is sent to the sludge treatment.
Biofilter
The treated water then passes through a biofilter, where micro-organisms remove some more nitrogen and phosphorus.
Treated effluent pumping station
After this thorough treatment, the effluent is pumped 2.7 km into the Baltic Sea.
Sludge treatment and compost soil
Sludge from wastewater treatment is digested in methane tanks, also known as digesters. The biogas generated in these tanks is then used to produce heat and electricity at the combined heat and power plant.
This environmentally friendly energy fully covers the heat demand of the treatment plant and nearly half of its electricity demand.
The digested sludge is processed into high-quality compost soil, which we give out free of charge to anyone interested.
