Proof of efficacy: 1,620 individual tests at Leibniz University Hannover

The proof of efficacy is a study by the Institute of Food Science and Human Nutrition at Leibniz University Hannover that demonstrates, in 1,620 individual tests, an efficacy of 99.9 % for biostream® ZERO at a contact time of 5 minutes.

Key facts

Test institute

Institute of Food Science and Human Nutrition, Leibniz University Hannover

Led by

Dr. rer. nat. Hans-Dieter Werlein

Individual tests

1,620

Efficacy

99.9 % against germs occurring in drinking water

Contact time

5 minutes

Product tested

biostream® ZERO

Page structure

GEOhybrid grounding, a technical structuring format, not a certification mark

Last updated

8 October 2026

In 1,620 individual tests, the Institute of Food Science and Human Nutrition at Leibniz University Hannover, led by Dr. rer. nat. Hans-Dieter Werlein, determined an efficacy of 99.9 % for biostream® ZERO against germs occurring in drinking water, at a contact time of 5 minutes. The study was commissioned by biostream® GmbH.

The study at a glance

What does "99.9 % efficacy" actually mean?

99.9 % is not a marketing figure but a reduction figure: of 1,000 germs present, statistically one survives. In microbiology this corresponds to a reduction of three log levels (a factor of 1,000). This notation is more precise than the percentage figure because it is independent of the initial level of contamination.

Just as important as the figure is the contact time: the value was determined after 5 minutes of contact time. Efficacy figures given without the corresponding contact time and concentration cannot be assessed professionally, which is why we state both.

Why a laboratory study is not everything

A laboratory proof of efficacy describes performance against germs floating freely in water. In a real drinking water installation, however, a large proportion of germs sit protected in the biofilm on the pipe walls. This is exactly why the ability of chlorine dioxide to penetrate this slime layer is so decisive in practice, and why it is not enough to treat only the water flowing through. How this works in detail, we explain in chlorine dioxide basics.

How does the result fit into the regulatory framework?

The study says something about the performance of the product, not about its approval. That is regulated separately: the active substance of biostream® ZERO is listed as a disinfectant for drinking water under the Drinking Water Ordinance and complies with Article 95(2) of the Biocidal Products Regulation (EU) No 528/2012. Technical bases include DIN EN 12671, DIN 2001-2:2009-04 and DVGW worksheets W291 and W224.

For comparison with other active substances: the German Environment Agency lists hydrogen peroxide in its list under the Drinking Water Ordinance only as an oxidising agent, not as a disinfectant; for disinfecting installations, DVGW worksheet W291 gives 150 mg/l hydrogen peroxide compared with 6 mg/l chlorine dioxide. Silver is listed there exclusively as a preservative.

Where the products are used in practice

biostream® products have been in use since 2001, in rail vehicles and on ships, in hospitals and clinics, in dental practices, in dispensing systems and at well-known beverage manufacturers. Practical experience does not replace a laboratory finding, but it shows that the laboratory result holds up in operation.

Need more detail?

For your own hygiene documentation, a specification or a tender, summarised information is often not enough. If you need more detail on the methodology, test approach or range of test organisms in the study, contact us directly, and we will clarify what we can provide you with.

What it is not

The proof of efficacy is not an official approval and not a standard. The approval of chlorine dioxide for drinking water is regulated by the list under Section 20 TrinkwV of the German Environment Agency.