Third party research

In conjunction with an updated edition of the DVGW (German Water Certifying Authority) handbook section W 130 (Water Well Rehabilitation Techniques), which should take into consideration the state-of-the-art rehabilitation techniques, an official research program was initiated by the DVGW in the year 1999.

The goal was to compare the various mechanical rehabilitation techniques and verify their efficiency by determining their penetration capabilities beyond the filter screens into the gravel pack. The investigations were carried out at the Dresdner Grundwasserforschungszentrume.V. (Dresdner Groundwater Research Centre) on real well models.

The results have been finalised in 2003 and were published in the DVGW Research edition W 55/99, in which the HPI-Process® has achieved best results compared to other rehab methods. The JET Master® was the only system to simultaneously perform loosening (breaking up of deposits), transport of loosened deposits and also its measurement / monitoring.

A further test of the actual efficiency of the HPI-Process® with the Etschel JET Master® was carried out by the Dutch Water Certifying Authority (KIWA WATER RESEARCH). This test shows the efficiency of the JET Master® during well development in sandy aquifer without gravel pack using Johnson screens.

Furthermore, our process was recommended as a “Best-Pratcise-Solution” by the Bavarian State Office for the Environment in 2015, after it was able to achieve an average performance increase of 69% at 18 wells in Bavaria. As a result, it was included in the drinking water guideline of the Bavarian State Office for the Environment.

In addition, we conducted our own test under the supervision of a DVGW certifier. To make visible what happens in the well during rehabilitation, we simulated a well in a swimming pool. To do this, we placed two filter pipes of different diameters on a metal plate at the bottom of the pool and filled the space between them with filter gravel. We also placed bags of hard iron-manganese chunks in the gravel space. We recorded the whole thing with a video camera. Firstly, it can be seen that the process creates cavitation, which is due to the negative pressure created inside the well. Furthermore, one can see the enormous depth effectiveness of the process. The pressure waves are still visible far behind the simulated borehole wall. After a few minutes, nothing is left of the hard iron-manganese chunks. See the whole video here.

All those researches were made with our old system, UNINOZ®. The angles of the nozzles were static at 90° from the vertical shaft.


We have worked with the UNINOZ system since 1993, when innitially introducing the HPI-Process® to the market. Although we have achieved very satisfying results for our customers, we were searching for an improvement for several well screen materials.

After years of research and field testing, we found out that hydraulic rolls occur by adjusting the angle of the nozzles (of our MAXINOZ® aggregate) to the filter screen material. This enhances the extraction of loosened deposits to a significantly higher level, thus resulting in even better specific capacity improvements.

In addition, the four different directions ensure that the loosening of the deposits increases sharply.

If you like to see more detail about the comparison between UNINOZ® and MAXINOZ® just contact us. We are happy to give you further information.