Purified drinking water for waterworks in Hungary - using only natural processes

12,000 inhabitants in the town of Tolna in Hungary, 135 km south of Budapest, are enjoying pure drinking water from a new water utility. The water utility is the first of its kind in Hungary, using no chemicals to make the water drinkable.

Historically, all drinking water in Hungary is produced using a treatment process of dosing oxidation chemicals followed by sand filtration. The chemicals widely used are sodium hypochlorite (NaOCl), potassium permanganate (KMnO4) and chlorine gas (Cl2).

For the project in Tolna only sand filtration and air was used to turn groundwater into drinking water - a method with low environmental impact as well as low complexity and low costs. 

Water source and water treatment method

World Health Organisation (WHO) guidelines are generally followed throughout the world for drinking water quality requirements. In addition to the WHO guidelines, each country or territory can have their own standards.

In the European countries the EU Drinking Water Directive must be followed. In general the selection of treatment method is greatly related to the water source available and to the standards set out by the local authorities. The following table shows different water sources, their related water treatment method as well as the level of complexity, costs and environmental impact.

Water sourceWater treatment methodComplexity
and costs


Sea waterDesalination.
Process of removing salts from the water using reverse osmosis.
Surface water (lakes, swamps, rivers)Chemical and mechanical treatment.
Flocculation, sedimentation, filtration and disinfection using chemicals for coagulation and disinfection.
GroundwaterChemical treatment
Pre-chlorination, dosing of oxidation chemicals and sand filtration.
Medium to highHigh
GroundwaterNatural processes
Treatment using atmospheric air and filtration in pressure filters.
Low to mediumLow to medium

The Tolna project

The water source in Tolna is groundwater from 60 meters deep well. The water contains impurities such as iron, manganese, hydrogen sulphide, and ammonium that must be removed in order to meet the standards of the EU Drinking Water Directive. 

ImpurityUnitGroundwater in Tolna

Quality requirements EU Drinking Water Directive

Drinking water quality in Tolna after treatment

Ironmg Fe/l1.70.20.02
Manganesemg Mn/l0.450.050.01
Ammoniummg NH4/l0.50.50.1

EUROWATER has designed, manufactured and installed the water treatment solution in Tolna. The groundwater is treated in pressure filters with selected filter media and atmospheric air. No chemicals are used in this treatment process. 

To ensure a safe and reliable production of clean drinking water, the solution in Tolna consists of four pressure filters in parallel operation. Each pressure filter has a capacity of 50 m³/h.

Filtration system with four pressure filters from EUROWATER. Aeration system with two compressors. Air blower for high quality backwash of the filter material. (Photos: Juraj Kalafut © Silhorko-Eurowater)  

The Danish model - a natural process

In Denmark the drinking water quality requirements are even tougher than the requirements in the EU Drinking Water Directive. The source of water is 100 % groundwater. The water treatment method used in Denmark is based on a philosophy using only natural processes such as oxidation and filtration. 

A EUROWATER pressure filter is specially designed for drinking water treatment without using chemicals in the treatment process. In a EUROWATER pressure filter the groundwater is oxidized with atmospheric air to aid the filtration process with sufficient filter media - individually designed for the project.

If designed properly, the chemical solution as well as the chemical-free solution will do the job: produce drinking water. However, there are some very clear benefits using only oxidation and filtration for producing drinking water.

Benefits using a chemical-free solution


Good work environment

Safe environment without handling or storage of dangerous chemicals.


No waste water problems

No risk of effluent water with traces of chemicals when using a natural filtration process.


Safe drinking water - everyday

No risk of residual chemicals in the drinking water.


Ease of operation

Dosing of chemicals requires a demanding operation and attendance as well as controlling and monitoring.


The commissioning of the water treatment in Tolna was performed in the beginning of 2012. The status is that the water quality has been very good and meets by far the required standards.


Technical information 

  • Flow 100 m3/h

Water Treatment Equipment 

  • 4 x Pressure filters TFB50
  • Aeration system
  • Air blower

More references from EUROWATER

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