The natural treatment
against iron, manganese & ammonium

No iron deposits
(ochre deposits)

Pure drinking and service water

directly from your well

Explanatory video - How does it work?

The subject of FERMANOX® water treatment is underground iron and manganese removal, in which water treatment takes place purely naturally with the help of oxygen directly in the water-bearing soil layers – effectively and efficiently – the FERMANOX® water treatment process.

Since groundwater usually contains iron and manganese due to a lack of oxygen and often also ammonium, groundwater requires treatment before it can be used. The FERMANOX® process is the most efficient method for removing these substances because it makes optimal use of nature’s mechanisms of action through underground treatment. This is why we can guarantee you water that is free of iron, manganese and ammonium. Since FERMANOX® only pumps treated water directly from the well, deposits and calcification in wells, pumps and pipes are also avoided.

With FERMANOX® water treatment, water enriched with atmospheric oxygen is fed via the borehole directly into the groundwater-bearing soil layers (aquifer). There, the groundwater is treated in a purely natural and particularly efficient manner.

After a short run-in period, a large, oxygen-rich area with optimal conditions for iron and manganese removal is created around the borehole. At the edge of this area – and thus already at a great distance from the well – a treatment zone (reaction chamber) is created in which iron and manganese are oxidized. In this zone, complex natural treatment mechanisms are activated as soon as groundwater containing iron and manganese enters. The iron and manganese oxides attach themselves to the grains of sand in the soil and form oxide layers. They are now present in a solid, poorly soluble form – and thus have no adverse effect on the quality of the groundwater in the soil. The size of the reaction chamber is determined by the water quality of the groundwater, the hydrogeology of the soil and the resulting infiltration amount of the oxygen introduced.

Inside the borehole, a zone is created that only contains pure, treated water of drinking water quality, i.e. the iron, manganese and ammonium concentrations of the water meet at least the limit values ​​of the drinking water regulations. This drinking water can be extracted and used directly from the well.

Principle of operation / functionality of the FERMANOX® process

Guaranteed drinking water quality

As a pioneer and market leader in compact systems for underground water treatment, FERMANOX® has the know-how to evaluate the hydrogeological and water-chemical conditions on site and the resulting design of the FERMANOX® water treatment plant.

The first FERMANOX® plant was put into operation in 1983. The iron content of the original raw water was 6.7 mg/l, which corresponds to 33.5 times the limit value according to the Drinking Water Ordinance. The plant has been running smoothly to this day, even though the borehole is now around 60 years old.

In the meantime, over 10,000 systems have been put into operation.

Thanks to this experience, FERMANOX® guarantees the treatment of water to drinking water quality (according to the valid TrinkwV 2001[1]) with regard to iron, manganese and ammonium.

Parameter Limit
Ammonium 0,5 mg/l
Iron 0,2 mg/l
Manganese 0,05 mg/l
In addition, FERMANOX® also guarantees compliance with or below the limit values ​​according to the Drinking Water Ordinance with regard to other oxidizable ingredients that occur less frequently, such as nitrite, arsenic, hydrogen sulphide and methane.

[1]Gesetzliche Grundlage ist die Trinkwasserverordnung in der Fassung der Bekanntmachung vom 28. November 2011 (BGBl. I S. 2370), die durch Artikel 2 Absatz 19 des Gesetzes vom 22. Dezember 2011 (BGBl. I S. 3044) geändert worden ist (zukünftig verwendet als Abkürzung: TrinkwV 2001)

No discoloration

Water treated with FERMANOX® is free of iron and manganese and therefore does not leave any brown or black discoloration when used. This keeps laundry, sinks, showers, bathtubs and tiles clean.

No deposits

Since underground treatment prevents iron and manganese deposits (calcification) on wells, pumps and pipes, cleaning or regeneration is no longer necessary.

The FERMANOX® system significantly extends the service life of your entire water supply system, as only pure, treated water flows through wells, pumps and pipes.

Submersible pumps after 5 years of operation with FERMANOX® (above) and a conventional gravel filter (below)

Maximum efficiency – minimum energy consumption

In contrast to conventional methods, the FERMANOX® system only requires a small amount of oxygen-rich water, which is fed into the aquifers for treatment, since the natural reaction zone in the area surrounding the well is many times larger than the filter volume of above-ground filters.

As a result, the energy requirement for the entire water supply is significantly lower than with conventional water treatment.

No maintenance – just checks!

Since the water treatment in the FERMANOX® process takes place in the aquifer itself, no regular maintenance is required, just an inspection.

In small FERMANOX® water treatment systems, the strainer in front of the system must be checked once a year to ensure that the oxygen enrichment performance does not drop due to blockages. Large systems are completely maintenance-free.

No filters, no backwash

In contrast to conventional methods, no above-ground filters are necessary. The water is naturally treated before it is pumped and used – without chemicals or replacement material.

Annoying and expensive replacement and disposal of filter material as well as backwashing of the filters are no longer necessary.

Requirements for the borehole

The basic requirement for using the FERMANOX® process is the presence of one or more boreholes in the loose rock (sand or gravel), because the actual processing takes place in the pores of the aquifer. The boreholes themselves must be created in accordance with the usual technical rules and (if there are several wells) with sufficient spacing and with the shortest possible filter sections. If there are several boreholes, the spacing must be agreed with us.

Row water quality

There are no application limits for iron or manganese concentrations in the raw water. FERMANOX® is even able to treat extreme groundwater to drinking water level, where the raw water values ​​are many times higher than the limit values ​​of the Drinking Water Ordinance. Demanganization in particular requires a minimum pH value of the raw water, which is lower than with above-ground processes due to the high efficiency of the process – without the addition of chemicals. With higher ammonium or methane concentrations in the groundwater, the treatment effort increases significantly.

FERMANOX® -Interpretation
The correct design of the FERMANOX® system is of crucial importance for the long-term optimal operation of the system. In order to check the requirements and offer a suitable water treatment system, we require the following documents:
  • Information on water requirements
  • Water analyses of existing wells
  • Data on well construction

We will be happy to carry out the necessary water analyses for you using raw water samples. Please send us a water sample for this purpose.

At any initial pH value, FERMANOX® water treatment achieves a higher degree of treatment than conventional gravel filters (without additives).

Groundwater that is difficult to treat: Epe, Netherlands; FERMANOX® plant WV 100-165 P
 Water Analysis Row water Pure water
Iron 14,525 mg/l 0,003 mg/l
Manganese 0,613mg/l 0,043mg/l
Ammonium 1,47 mg/l 0,18 mg/l
pH-value 6,01

Groundwater that is difficult to treat: Fattening pig farm Molbergen, NRW; FERMANOX® plant WV 50/4/28 P

Water analysis Fountain 1 Fountain 2
Row water values
Iron 5,84 mg/ 6,54 mg/l
Manganese 0,143 mg/l 0,092 mg/l
Ammonium 0,052 mg/ 0,068 mg/l
pH-value 5,635,59 5,59
Karbonathärte 0,38 °dH 0,44 °dH

Groundwater that is difficult to treat: Schwarzenbrock, Bavaria; FERMANOX® plant BZ 63 P

Water analysis Row water Pure water
Iron 1,95mg/l 0,02mg/l
Manganese 0,941mg/l 0,024mg/l
Arsenic 0,027mg/l 0,002 mg/l

In contrast to above-ground filter systems, underground iron and manganese removal (UEE) uses the aquifer itself in the area close to the well as a reaction space and for the retention of the reaction products. Within the reaction space, the oxygen introduced activates the complex treatment mechanisms. The chemical-physical processes are supported by an autocatalytic effect of the already determined oxides. Microbiological processes also play an important role.

The oxidation of the dissolved iron can be expressed, for example, using the following molecular formula:

2 Fe2+ + ½ O2 + (x + 2) H2O → (Fe2O3 * x H2O) + 4 H+[1]

In conventional above-ground filters, aeration produces predominantly amorphous, water-rich iron(III) hydroxide (Fe(OH)3) and manganese oxide hydrate (MnOOH), and thus large quantities of sludge that must be backwashed and disposed of.

Underground, the primary reaction product iron(III) hydroxide is converted into crystalline iron(III) oxide hydrate and manganese(III) oxide hydrate into manganese dioxide (MnO2, “manganese dioxide”). The products form fine coatings on the soil grain surface with high density and correspondingly low volume.[1]

Iron and manganese oxide hydrates deposited on the soil grain lead to a high adsorption capacity for iron and manganese ions in the extraction phase. The oxygen introduced during the infiltration phase reaches the iron and manganese ions adsorbed on the grain surface as it flows through the aquifer and oxidizes them to poorly soluble compounds. Part of the oxygen is adsorbed and is still available for oxidation at the start of extraction.

Adsorption-oxidation model – chemical-physical processes in the reaction space of the UEE (courtesy of Prof. Dr.-Ing. U. Rott).

In addition to iron and manganese removal, the introduced oxygen causes other positive reactions in the aquifer:

  • Nitrification of ammonium and nitrite[2]: Ammonium and/or nitrite in groundwater are nitrified and thus significantly reduced. The conversion always takes place bacteriologically and in the case of ammonium always in two stages. 2 NH4+ + 3 O2 2 NO2 + 2 H2O + 4 H+ (+ Energy) by Nitrosomonas and Nitrosocystis 2 NO2 + O2 2 NO3 (+ Energy) by Nitrobacter and NitrosocystisThe resulting biomass is small and usually of no importance.
  • Hydrogen sulphide and the unpleasant smell associated with it are eliminated by oxidation.
  • Heavy metals such as arsenic, nickel, etc. can be reduced. Since these substances are deposited in the iron oxidation products, it is necessary that the groundwater has a minimum iron content.[3]
  • When oxygen is introduced into the groundwater, methane oxidizes before iron in the aquifer, resulting in a relatively high biomass formation when oxygen demand is high; a special operating mode is therefore required for groundwater containing methane.


By appropriately designing an underground water treatment system, all of the above reactions take place in the aquifer outside the well structure, through which only pure water flows.

[1] Rott, Ulrich: Gutachterliche Stellungnahme zur Wirkungsweise der ”FERMANOX-Wasseraufbereitung” unter besonderer Berücksichtigung umweltrelevanter Auswirkungen. Universität Stuttgart, Institut für Siedlungswasserbau, Wassergüte- und Abfallwirtschaft, 1994

[2] Rott, Ulrich: Gutachterliche Stellungnahme zur Aufbereitungsleistung der ”FERMANOX-Wasseraufbereitung”. Universität Stuttgart, Institut für Siedlungswasserbau, Wassergüte- und Abfallwirtschaft, 1995

[3] Rott, Ulrich; Meyerhoff, Ralf ; Bauer, Tarja: In situ-Aufbereitung von Grundwasser mit erhöhten Eisen-, Mangan- und Arsengehalten. In: gwf – Wasser/Abwasser 137 (1996.) Nr. 7, S. 358-363

from the expert

Guaranteed iron and manganese free water, directly from your well

Water treatment

unleash your

inner athlete

physical fitness

Join The Gym Group for a wide range of classes and high-spec equipment.

The Gym Group is the original provider of high quality, low cost gym facilities in the UK.




build your

ideal body

physical fitness

Join The Gym Group for a wide range of classes and high-spec equipment.

The Gym Group is the original provider of high quality, low cost gym facilities in the UK.




WordPress Cookie Plugin by Real Cookie Banner