Poland has a lower proportion of residents connected to sewerage networks than other countries in the Baltic Sea region. Around 2.5 million septic tanks and domestic wastewater treatment systems are currently in use across the country, according to a report by the Race For The Baltic Foundation and the Environmental Protection Support Agency.
The main problem is that the vast majority of wastewater from these systems does not reach treatment plants. Instead, it enters the natural environment, contaminating soil, groundwater and rivers before eventually reaching the Baltic Sea.
The report estimates that approximately 200 million cubic metres of wastewater enter the environment every year. This is equivalent to almost one-third of the volume of Lake Śniardwy, Poland’s largest lake.
“The Baltic Sea is an ecosystem in which the water is replaced only once every 30 years. This means that everything entering the sea remains there for decades, and the ecosystem has very limited capacity to regenerate,” Marcin Kotlarek, president of the Race For The Baltic Foundation, told the Newseria news agency.
“What we can do here and now is reduce the pollution flowing into the sea from land. This requires action at the source, including good cargo-handling practices in ports, proper management of waste generated during fertiliser production, responsible agricultural fertilisation and effective wastewater management.”
Wastewater contributes to Baltic Sea eutrophication
According to the report, wastewater is responsible for approximately 35% of the phosphorus entering the Baltic Sea each year.
Phosphorus is one of the substances contributing to the eutrophication of the sea. Excessive levels encourage the growth of algae and cyanobacteria and contribute to the creation of oxygen-depleted zones.
This leads to the degradation of aquatic ecosystems and a decline in water quality.
The authors of the report argue that the scale of the problem reflects the specific weaknesses of Poland’s wastewater management system. In this respect, Poland performs worse than other Baltic Sea countries.
Poland’s compliance with the requirements of the European Union’s Urban Wastewater Treatment Directive is estimated at between 70% and 77%. In other countries in the region, the figure ranges from 96% to 100%.
“In Poland, one in four people is not connected to a sewerage network. This means that around 10 million people live in homes equipped with either a septic tank or a domestic wastewater treatment system,” Kotlarek said.
“Poland has more than 2.1 million registered septic tanks, over 200,000 unregistered tanks operating in the grey economy and an additional 500,000 domestic wastewater treatment systems.”
He noted that a sewerage connection rate of approximately 72% is not necessarily a problem in itself.
“It does not always make economic sense to connect every village and every household to a sewerage network. The problem is how people use and maintain septic tanks and domestic wastewater treatment systems.”
Up to 90% of wastewater may not reach treatment plants
Calculations presented in the report, based on data from Statistics Poland, indicate that 45 million cubic metres of liquid waste were collected in Poland in 2024.
However, the expected amount should have exceeded between 250 million and 300 million cubic metres.
“This means that between 80% and 90% of wastewater does not reach treatment plants. We are talking about approximately 200 million cubic metres,” Kotlarek said.
“For comparison, Lake Śniardwy contains around 600 million cubic metres of water. Every year, wastewater equivalent to one-third of the lake’s volume enters soil, groundwater, rivers and lakes. The scale is enormous.”
Helena Goderska, director of the Project Implementation Office at the Environmental Protection Support Agency, highlighted the regional dimension of the problem.
In the Podkarpackie Province, more than 95% of wastewater generated by individual systems may enter the environment. This amounts to approximately 13.7 million cubic metres annually.
That is almost twice the amount of sewage released into the Vistula River during the failure of Warsaw’s Czajka wastewater treatment plant.
Experts warn that leaking septic tanks and illegal discharges into drainage ditches or directly into the ground introduce dangerous bacteria and chemicals into the soil. These pollutants can then enter local drinking-water sources.
Leaking septic tanks threaten public health
“This has an impact on public health,” Kotlarek said. “A recent example was Olecko, where residents had no access to drinking water for several days after E. coli bacteria contaminated the local water supply.”
“People are also affected locally because leaking septic tanks contaminate wells, which are still frequently used as a source of drinking water in rural areas.”
The problem has several causes. The first is the age and technical condition of septic tanks and domestic wastewater treatment systems.
Many installations are old, poorly constructed or made using unsuitable materials. Replacing them would require substantial financial support from the national government, municipalities and homeowners.
The Race For The Baltic Foundation estimates that several billion złoty would be needed to modernise the existing infrastructure.
Another cause is the improper operation of installations and the irregular emptying of septic tanks. Experts also point to insufficient supervision by local authorities.
Municipalities lack consistent monitoring systems
“Municipalities often do not have uniform standards,” Kotlarek said. “In some areas, the rules require a septic tank to be emptied only when it is full, while in others it must be emptied once every quarter. These standards are often very flexible.”
Another problem is the lack of digital monitoring.
“Two-thirds of municipalities do not have IT systems that would allow them to monitor how frequently individual households have their wastewater collected and delivered to treatment plants,” he said.
“This is very simple to measure, monitor and report. Municipalities should establish clear regulations, supervise how frequently households dispose of wastewater and ensure connections to sewerage networks in designated urban areas.”
“These are municipal responsibilities that are often not being fulfilled.”
According to the report’s authors, regional environmental protection inspectorates also provide insufficient oversight of municipalities.
“Only 20% of municipalities are inspected by regional environmental protection inspectorates each year,” Kotlarek said.
The Baltic Sea begins on land
Experts stress that uncollected wastewater represents a serious environmental challenge that cannot be ignored.
The issue is highlighted by the educational campaign “Do You See Cyanobacteria?”, organised by the Race For The Baltic Foundation as part of the “The Baltic Sea Begins on Land” project.
The campaign aims to demonstrate that decisions made far from the coast have a direct impact on the condition of the Baltic Sea, which is considered one of the world’s most environmentally vulnerable seas.
