For water utilities and industrial well operators, a decline in well yield rarely occurs suddenly; it is usually the result of progressive clogging (e.g. iron and manganese deposits) and the ageing process, both of which reduce specific capacity over time. This is also reflected in the operational practice described in the context of DVGW W 130. In large supply systems, even moderate losses can impact availability, energy consumption and maintenance cycles downstream. This is why operators such as Hessenwasser have evaluated modern, chemical-free rehabilitation methods, identifying processes that combine measurable efficiency with reliable execution expertise.
Field evaluation: HPI-Process® is the preferred method for high water pressure
In a series of comparative tests conducted in 2018 in an area prone to iron and manganese deposition, Etschel Brunnenservice was commissioned to rehabilitate a 50-metre-deep well (drilled in 1963) equipped with a DN400 wooden (OBO) filter screen. The well was treated using the established UNINOZ® bi-rotational system, which generates high-pressure impulses (HPI Process®) horizontally to the well axis. Pumping tests and geophysical measurements documented a specific capacity improvement from 26 to 41.3 m³/h per metre of drawdown — an increase of 58% — with most of the solids being removed during the HPI treatment itself. Subsequent surge plugging mobilised only small additional volumes of sand.
The MAXINOZ® change: adjustable nozzle angles for screen-specific treatment
Building on these outcomes, Hessenwasser later tendered the rehabilitation of two 90-metre agricultural wells, including pre-cleaning and brushing, as well as comparative methods. The operator opted for the JET Master® rehabilitation approach, utilising the MAXINOZ® bi-rotational nozzle unit, which is supplied exclusively by Etschel Brunnenservice for this purpose. The key technical distinction between MAXINOZ® and UNINOZ® is that MAXINOZ® allows the angles of the nozzles to be adjusted to match the material of the filter screen, thereby improving the targeting of high-pressure impulses across different screen designs. Between 2016 and 2021, MAXINOZ® was practically applied to common construction materials in Germany, and documented projects showed substantial increases in capacity and performance in multiple well configurations.
Short operating time, high solids discharge and significant Qspec gains.
The Lampertheim order included pumping tests and geophysical measurements (packer flowmeters) before and after rehabilitation, as well as TV inspections and cleaning of the heavily clogged pumps and risers that were observed during pump removal. During the HPI rehabilitation process using MAXINOZ®, well 3 discharged 0.16 m³ of sand and 1.29 m³ of solids within three hours (with a total water flow of 226.8 m³) until the DVGW W 130 termination criterion was reached. Well 4 discharged 0.50 m³ of sand and 1.04 m³ of solids within four hours (with a total water flow of 288 m³). The measured specific capacity increased from 8.62 to 21.27 l/s/m in well 3 (+246%), and from 3.98 to 16.39 l/s/m in well 4 (+411%). The report also notes that such results can improve sustainability by extending rehabilitation cycles and reducing downtime, as wells can be returned to operation sooner than with multi-day alternatives.
Throughout the documented fieldwork, the MAXINOZ® nozzle rotation unit for the HPI Process® (JET Master® system) is presented as a tried-and-tested option for well development and rehabilitation. In many cases, it has the potential to deliver higher Qspec outcomes than previous configurations while requiring comparatively short operating times. For operators seeking to balance water security, maintenance windows and lifecycle costs, the core practical benefit described in the field reports is the combination of targeted impulse application and efficient solids removal.
To view more detailed data and diagrams, as well as the complete field report, please click the PDF button.
If you would like to evaluate rehabilitation options for your wells, or determine which method best suits your screen material and site conditions, Etschel Brunnenservice GmbH can support you as a specialist partner. Contact us with your well data to discuss the next steps.
