Hydrojetting and biofilm: why clearing the blockage is only half the battle

Hydrojetting is not the magical fix-all solution. When production lines keep failing quality checks despite regular high-pressure water jetting the blockage may be cleared, but there are still micro-organisms left behind. Relying solely on hydrojetting is a costly overestimation of what mechanical cleaning can actually achieve.

What is hydrojetting?

Hydrojetting uses highly pressurised water to physically dislodge and flush out deposits, scale, sludge, and organic residue from the inner surfaces of pipes and process lines. It is a proven, well-established tool for restoring hydraulic capacity and reducing surface fouling in a single operational cycle. The tool itself isn't flawed: it is simply designed to solve a mechanical problem. However, in process environments where biofilm is the root cause of contamination, mechanical solutions are often not enough.

The downsides of hydrojetting

While hydrojetting may be good at clearing any mechanical blockages within process water systems the biofilm can continue to grow if the microbiological issue isn’t solved. Even after a high pressure cleaning there are still bacteria left behind that can grow into a new resilient biofilm again (1). Hydrojetting alone is therefore not enough and should be followed up with disinfection in order to get the pipes not just unclogged, but microbiologically clean.

Furthermore, every process line has corners, dead ends, and hard-to-reach sections where the water jet simply does not arrive with enough force to fully remove biofilm (1). These spots can recontaminate the system starting from the moment cleaning is done. There are also very high costs attached to the method.

A well-known example is the 2013 Fonterra incident, in which whey protein concentrate was contaminated with Clostridium botulinum. The contamination was not caused by a lack of cleaning. Biofilm had simply survived standard cleaning.(3).

Hydrojetting is also water-intensive and the wastewater that it produces is full of microorganisms and needs proper disposal. Due to very high pressure there is also a risk of damage to your system.

Hydrojetting's strengths: where It performs

Hydrojetting is genuinely good at what it was designed for. It clears blockages, removes scale and loose deposits, and leaves pipe surfaces visibly cleaner. On straight, accessible sections it can also knock back thinner biofilm layers that have not yet fully developed. When combined with appropriate chemical pre‑treatment to soften biofilm, it can be even more effective.

It also can help with the following: 

• Restoring the waterflow: blocked or clogged pipes are cleared quickly and reliably.
• Reducing the organic material in pipes: less residue means less food for bacteria to grow on.

The headache of incomplete removal

The real danger of relying solely on jetting is that a partial clean is vulnerable to rapid regrowth. The bacteria left behind in the microscopic crevices immediately begin to multiply, and because jetting adds nothing to the water itself, this reattachment happens the moment production restarts (2).

For QA managers, the consequences of this cycle are painfully familiar: elevated microbial counts in routine water sampling, unexplained Out-Of-Specification (OOS) results, and quality issues that resurface mere days after a major cleaning cycle. Each jet clean might make the pipes look pristine, but without continuous disinfection, you are simply resetting a ticking clock. The next failed audit or costly product recall remains just a matter of time.

Closing the gap with continuous HOCl disinfection

The solution to what hydrojetting leaves behind is not more jetting: it is continuous disinfection. And specifically, it is the kind of disinfection that works with your process water rather than requiring production stops, chemical deliveries, or additional PPE and therefore helps you save costs.

The Watter-system produces HOCl (hypochlorous acid) on-site, on demand, from nothing more than water, salt, and electricity and produces a proven effective disinfectant against bacteria, viruses, fungi, and yeasts. It is also highly effective against biofilm, even at low concentrations.

Because the disinfectant is generated continuously at the point of use, there is no need for storage or transport of hazardous chemicals. You also have fresh disinfectant available whenever it is needed. The system doses a low concentration of HOCl directly into the process water stream, maintaining continuous disinfection throughout the entire circuit, including the dead ends, pipe bends, and low-flow zones that a water jet cannot reach. This is the critical difference between a periodic deep clean with hydrojetting and a constant disinfection using HOCl. 

Why the combination works

Hydrojetting and in‑situ HOCl disinfection with Watter are not competitors, but are two parts of the same solution (4). Jetting makes sure that the system is cleaned mechanically: it removes scale, sludge, and the thick biofilm layers that you can reach and see. HOCl then takes over after cleaning and during production. It keeps the water itself disinfected so that microorganisms cannot easily rebuild new biofilm on those freshly cleaned pipes.

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HOCl also helps with:

• Disinfecting after the cleaning: jetting deals with the physical blockage; continuous HOCl tackles the remaining microorganisms in the water and on the surface so the same problem does not quietly rebuild between cleans, which also will reduce the frequency in which you need to use hydrojetting
• More effective control: Continuous biofilm‑control strategies improve microbiological control and help with the overall effectiveness of routine cleaning by adding a disinfection step (5).
• Lower QA workload and more stable production: with microbiological growth under better control, there are fewer repeat OOS results, fewer re-cleans of the same line, and less time lost on investigations and resampling after unexpected spikes in counts.
• Reaches where jets cannot: because HOCl moves with the water, it also treats corners, dead ends, valves, and other low‑flow areas that a nozzle cannot hit with enough force; which handles a critical weakness of hydrojetting and gives you peace of mind with more complete disinfection.

References

1. Simunič, U., Pipp, P., Dular, M., & Stopar, D. (2020). The limitations of hydrodynamic removal of biofilms from the dead-ends in a model drinking water distribution system. Water Research, 178, 115838. https://doi.org/10.1016/j.watres.2020.115838
2. Douterelo, I., Husband, S., Loza, V., & Boxall, J. (2016). Dynamics of Biofilm Regrowth in Drinking Water Distribution Systems. Applied and Environmental Microbiology, 82(14), 4155–4168. https://doi.org/10.1128/aem.00109-16
3. Industries, M. for P. (2013). NZ Government. New Zealand Government. https://www.mpi.govt.nz/dmsdocument/3760-Whey-Protein-Concentrate-Incident-Tracing-and-Verification-Report
4. Oliveira, I. M., Gomes, I. B., Simões, L. C., & Simões, M. (2024). A review of research advances on disinfection strategies for biofilm control in drinking water distribution systems. Water Research, 253, 121273. https://doi.org/10.1016/j.watres.2024.121273
5. Dawan, J., Zhang, S., & Ahn, J. (2025). Recent Advances in Biofilm Control Technologies for the Food Industry. Antibiotics, 14(3), 254–254. https://doi.org/10.3390/antibiotics14030254