The Best Hot Water Disinfection Options – A Comparison
The most commonly used disinfection methods for water treatment are:
Methods for Drinking Water Disinfection and Their Challenges
The disinfection of drinking water is essential to prevent the spread of waterborne diseases and to ensure safe drinking water quality. Various methods are used for this purpose, based on chemical biocides, thermal disinfection, or UV radiation. However, each of these methods comes with its own disadvantages—both for human health and the environment. Against this backdrop, there is a growing search for environmentally friendly and lower-risk alternatives that are just as effective while avoiding the drawbacks of conventional methods.
Issues and Health Risks of Using Biocides
The use of chemical biocides for water disinfection poses significant health and environmental risks. In particular, the use of chlorine can result in the formation of byproducts, including trihalomethanes (THMs) and haloacetic acids, which are potentially carcinogenic. Furthermore, biocide residues often leave toxic traces that can harm aquatic organisms in natural ecosystems. Repeated use of such disinfectants also promotes the development of resistant and resilient microorganisms, which can ultimately diminish the effectiveness of these substances. Additionally, biocides can cause unpredictable and irreparable damage to older water installations.
For these reasons, the use of biocides for drinking water disinfection is heavily regulated. Beginning January 1, 2025, a self-service ban on biocide products will come into effect in retail, mail-order, and online trade to restrict uncontrolled access and potential misuse.
Challenges of Thermal Disinfection
Thermal disinfection of drinking water is a controversial method due to its numerous disadvantages. Commonly used heating coils are primarily designed to heat water rather than effectively combat bacteria. Even professionals in the field of gas and water installation do not confirm the efficacy of this method. Additionally, it requires significant energy to reach the necessary temperatures of 70 to 80 °C and leads to high water consumption, as the entire piping system must be flushed. This can damage the materials of the drinking water installation, increase the risk of scalding, and promote system calcification.
In addition to high maintenance and energy costs and only short-term effectiveness, there is a risk of microorganisms from dead-end and branch pipes migrating back into flushed areas (circulation pipes), rendering the method inefficient. Furthermore, thermal disinfection is not recognized as an official disinfection method under § 20 of the German Drinking Water Ordinance.
UV Disinfection of Drinking Water
UV disinfection is another method for disinfecting drinking water, but its effectiveness strongly depends on proper application. UV light in the range of 250 to 270 nm (UVC) damages the genetic material of bacteria and fungi, thereby inhibiting their growth or killing them. A key factor for high disinfection performance is the residence time of the water in the UV lamp. If the water flows too quickly through the UVC lamp’s cylinder, the exposure is insufficient, significantly reducing its effectiveness.
Complete destruction of microorganisms is necessary because they can reverse UV-induced damage using internal processes, such as specific enzymes. If this occurs, there is a risk of
increased microbial growth and higher resistance to UV radiation.
Additionally, UV disinfection cannot remove biofilm that forms inside pipes, which serves as a breeding ground for pathogens.
Effective Alternative to Chemical, Thermal, and UV Disinfection
Hydrophysical Method – VA-Hydro Complete
Regulation (EU) No. 528/2012 mandates risk-minimized and sustainable methods for drinking water treatment. Therefore, biocide products must be compared with non-chemical alternatives during approval and renewal processes to promote effective and environmentally friendly solutions. Innovative water disinfection methods are to be prioritized if they are more effective and sustainable than existing ones.
The VA-Hydro Complete system offers such an alternative. It operates without biocides, thermal disinfection, or UV radiation and combats Legionella and biofilm through cavitation and flow dynamics. A key advantage is its effective removal of microorganisms and biofilm, even in dead-end and branch lines, which chemical, thermal, and UV methods cannot achieve. This makes the system a more efficient, environmentally friendly, and cost-effective disinfection method.
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Comparison of Disinfection Methods – Hot Water
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| Biocides | Thermal Disinfection | UV Disinfection | Hydrophysical Method | |
| Microorganism Destruction | Yes | Yes | Yes | Yes |
| Biofilm Removal | No | No | No | Yes |
| Reaches Dead-End Pipes | No | No | No | Yes |
| Removal of biofilm in branch lines | No | No | No | Yes |
| Cost-Effective | No | No | No | Yes |
| Requires Frequent Reapplication | Yes | Yes | Yes | No |
| Environmental Impact | Yes | Yes | Yes | No |
| Safe Application | No | No | No | Yes |
| Microorganism Resistance | Yes | Yes | Yes | No |
| Material Wear | Yes | Yes | Yes | No |
| Use in Mixed Installations | No | No | Yes | Yes |
| Easy Operation | No | Yes | No | Yes |
Download
Biocide Regulation
The Regulation (EU) No. 528/2012 of the European Parliament and of the Council of May 22, 2012, concerning the making available on the market and use of biocidal products, can be downloaded as a practical PDF.
List of Approved Treatment Substances and Disinfection Methods
The list of approved treatment substances and disinfection methods under § 20 of the German Drinking Water Ordinance can also be downloaded as a practical PDF in German.