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European Green Capital Award Good Practices - Helsingborg - 3 Pipe Wastewater System

EU Green Capital Finalist 2023

The innovative “Tre Rör Ut” (Three Pipe Wastewater) system collects and separates municipal wastewater closest to the source: in people’s houses. It prevents pollution, limits carbon emissions and saves water. It is important to educate people well in using the system to achieve optimal results, as seen when implemented in Helsingborg.

Starting situation

The municipality of Helsingborg decided in 2013 that they were going to build a new neighbourhood, Oceanhamnen, in the downtown area of the city. Based on successful cases in other countries, such as Germany and the Netherlands, it was decided to use a 3 pipe wastewater system.

This decision was part of an environmental plan for the neighbourhood. NSVA, a non-profit public water utility organisation, has been involved in the project. NSVA uses RecoLab, a development facility with a testing location for research. The plant is a unique wastewater system that recycles resources from sewage and food waste.

Helsingborg Factsheet
Helsingborg City Hall


The 3 Pipe Wastewater system was implemented as a cooperation between Helsingborg and NSVA. The system works by collecting water from showers, sinks (grey water) and toilets (black water). In addition, organic waste is collected via food grinders in the kitchen sinks. These make up the three pipes system. 

The organic waste and black water collected produces biogas and biofertiliser. This system, operating at RecoLab, currently generates 60-70% more biogas per person per year than a conventional sewage treatment plant. Besides this, compared to a normal wastewater treatment plant, this method recovers 3 times more phosphorus and 7 times more nitrogen per person per year. The collection system meets several environmental goals such as reducing over fertilisation, reducing negative effects on the climate and reducing water use. The system also reduces emissions of climate-impacting gases, nitrous oxide and carbon dioxide. Furthermore, it is an energy-efficient way to remove medicine residue.


One of the biggest challenges was to get citizens to understand how to use the organic waste grinder in the kitchen sink. As you cannot just throw any type of food in the sink, it has caused anxiety about using it. The grinder can get clogged fairly easily, which needs to be fixed by a plumber. The learning process takes a while before citizens are fully used to it. 

Another challenge was communication throughout the whole process, especially with the constructors. The vacuum toilet, for example, if installed correctly, can have nearly the same amount of decibels as a normal toilet. If not, it can be much louder and prove to be a nuisance to the inhabitants of the building. 

Aside from these challenges, it is interesting to note that because the food grinder was implemented at the same time as the vacuum toilet, the vacuum toilet barely got any resistance, as it can be much louder than a normal toilet. The speculation is that, because they were implemented together, the food waste is more difficult to get used to so the toilet is accepted more easily.


Helsingborg found this project so successful that the city intends to apply the same strategies again in the near future in the city district of “Östra Ramlösa”. The city of Visby is also currently building the same system.

Learnings and recommendations

Communication needs to be prioritised in future projects. It is important to make sure that communication is clear and it is explained how new installations work, what provides the best outcomes, and what problems to watch for.

This system can clean polluted and contaminated water perfectly. It is therefore a great option for countries or locations that deal with drought. As the processed water turns out very clean, it can be reimplemented for all purposes, including drinking water.

Find out more: visit RecoLab