Disinfecting process water is essential for maintaining the highest product quality. There are many different disinfection methods, so choosing the right one can be difficult. One of the better-known methods is UV-C disinfection, which effectively eliminates microorganisms in industrial environments. However, there are drawbacks to UV-C disinfection. An alternative such as the Watter system may therefore be more suitable.

How does UV-disinfection work?

UV-C disinfection is widely used in the industrial sector to disinfect process water and ensure its quality. UV disinfection is often used as the final step at the end of the supply system, just before the water is used in the process. A UV-C lamp damages the DNA or RNA of microorganisms, preventing them from reproducing and spreading.

This works perfectly for the water flowing past the lamp at that moment. Furthermore, UV disinfection does not affect the taste, odor, color, or pH of your product. This is precisely why many QA managers choose this method (1).

Factors to consider with UV disinfection:

1. Costly: UV-C disinfection is expensive. After the initial investment, the ongoing costs do not stop. Regular maintenance, such as replacing lamps to maintain optimal performance, can result in significant costs over the years. On average, a replacement lamp costs between €200 and €500, excluding labor costs.
2. Recontamination: Because UV-C only disinfects the water at the location where the lamp is installed, there is a risk of recontamination by microorganisms originating from biofilm further down the system.
3. Supplementary disinfection: UV-C disinfection kills microorganisms only at the specific location where the lamp is installed. However, biofilm will continue to build up and colonize throughout the water pipes. Therefore, chemical disinfection must still be performed regularly.
4. Microbial count reduction: UV-C disinfection eliminates 99.99% (log-4) of microorganisms, while the Watter system eliminates 99.999% (log-5).

Log 4 vs. log 5: How big is the difference?

To compare their effectiveness, the UV-C lamp has a log reduction of 4, while HOCl has a log reduction of 5. This means that the UV-C lamp eliminates 99.99% of microorganisms, while HOCl eliminates up to 99.999% of microorganisms on a given surface. It may not seem like a big difference, but suppose there are 1,000,000 bacteria present: after using UV-C disinfection, 100 bacteria would still remain, whereas with HOCl, only 10 would remain.

• After UV (log 4): 100 bacteria remain.
• After HOCl (log 5): 10 bacteria remain.

Suppose those bacteria double every 15 minutes. After 5 hours, the situation looks like this:

• UV: over 104.8 million bacteria.
• HOCl: over 10.4 million bacteria.

A difference of about 94 million bacteria starting from the same baseline, all because of that single decimal place. And that’s even before you factor in the biofilm that’s already in front of the UV lamp.

What are the limitations of UV disinfection?

A water distribution network is not a straight pipe with a single lamp at the end. It is a network of bends, couplings, storage tanks, and dead ends. It is precisely in these areas that microorganisms settle. There, a biofilm forms: a slimy layer of cooperating microorganisms that adheres to surfaces, protects itself, and continuously releases new bacteria, yeasts, and molds into the water.

The problem: that biofilm builds up in front of the UV lamp. While UV does kill the individual cells passing by at that moment, it does not target the microbial buildup located elsewhere in the system. And because biofilm multiplies exponentially, treatment at a single point is often simply not enough.

This has two specific consequences:

• Blockages: Biofilm builds up into a layer that impedes flow and can clog pipes.
• MIC (microbiologically induced corrosion): The substances secreted by biofilm-forming microorganisms can corrode materials such as metal, concrete, rubber, and plastic. This shortens the lifespan of your pipes and can lead to leaks.

In short: UV protects the water at the metering point, but not the system surrounding it.

UV vs HOCl

The Watter System

The Watter System is a machine that produces disinfectant with HOCl as the active ingredient on-site (in situ). Only water, salt, and electricity are needed to produce the disinfectant. The installation consists of a salt and storage tank connected to the system. It is linked to the process or drinking water via one or two dosing pumps that automatically dispense the precise amount of disinfectant into the water distribution system.

What makes Watter a good solution:

1. Low operating costs: Although an initial investment is required, production costs are exceptionally low due to the simple addition of salt to the system. This not only ensures long-term cost savings but also significantly reduces labor time, as the Watter disinfection solution disinfects the entire water distribution system.
2. Continuous biofilm control: HOCl removes and prevents biofilm buildup when dosed continuously. Therefore, additional disinfection and cleaning of the pipes is not necessary.
3. More sustainable production process: Since HOCl occurs naturally, it is biodegradable. The ecological footprint is reduced through in-situ production, as there is no need to deliver jerry cans of disinfectant to your facility.
4. Effectiveness: HOCl is highly effective against a wide range of bacteria and destroys up to 99.999% of them. Furthermore, it removes biofilm and, with continuous dosing, prevents its recurrence.
5. Certified and proven: Watter is officially registered on the European Article 95 list (EU 528/2012) and has received final Dutch Ctgb approval. The system is approved for PT-4 and has been successfully tested against EN 1276, EN 1650, EN 14476, EN 13697, and EN 1362/13623
6. Easy implementation: The Watter-system connects to your existing water distribution system using a dosing pump; therefore, replacing the entire system is not necessary.

References

1.  Mohaghegh Montazeri, M., Hejazi, S. A., & Taghipour, F. (2025). Ultraviolet light-emitting diode (UV-LED) water disinfection photoreactors: A review. Journal of Environmental Management, 386, 125678. https://doi.org/10.1016/j.jenvman.2025.125678
2. Singh, Harpreet, et al. “UVC Radiation for Food Safety: An Emerging Technology for the Microbial Disinfection of Food Products.” Chemical Engineering Journal, vol. 417, 1 Aug. 2021, p. 128084, www.sciencedirect.com/science/article/abs/pii/S1385894720342005, https://doi.org/10.1016/j.cej.2020.128084.