UBA: 2013. Assessment of the disinfectant efficacy in drinking water production or drinking water distribution network. Bactericidal and virucidal activity (based on -Umwelt Bundesamt–German Federal Environment Agency: Quantitative determination of the efficacy effect of disinfectants that are introduced into water intended for drinking water production, or into drinking water in the distribution network).
Test not accredited in our laboratory.
The main pathogens that can spread through water include bacteria (such as Campylobacter and enterohemorrhagic Escherichia coli), viruses (including Norovirus, Adenovirus, and hepatitis viruses), and parasites (such as Cryptosporidium and Giardia). Drinking water disinfectants should be applied in the minimum volume essential to achieve the desired effect and under conditions that optimize their effectiveness. Currently, there are no disinfectants available that eliminate Cryptosporidium oocyst and Giardia cysts in the concentrations commonly used for disinfection of drinking water and, therefore, this group is not considered in this test method.
The UBA method describes a test equipment and procedure to evaluate whether a disinfectant has sufficient bactericidal and virucidal effect for safe application in the drinking water supply. To simulate the drinking water treatment conditions, the test is carried out in a test system with continuous water flow, which simulates the application conditions in water plants in real practice. The test system consists of a long PVC pipe through which water circulates in a continuous flow (close to 350 L/h) into which the test organisms and the disinfectant are dosed. The system consists of sampling taps at different positions in the tubing that represent different contact times of the disinfectant with the test microorganism. After going through the test system, the test water is discarded. The test water conditions (temperature, pH and inorganic carbon) will be tap water conditions to simulate real conditions of use and will be measured and reported in each test. First, the test microorganisms in the water are added (Escherichia coli and Enterococcus faecium for bactericidal activity, and bacteriophages MS2 and PRD1 for viricidal activity), and their concentration is checked by taking a sample of the water with the microorganisms in tap 0 (negative control without disinfectant). Subsequently, the disinfectant is injected into the water flow. Organisms and disinfectant mix thoroughly with the water as the small diameter of the test tubing ensures turbulent flow. Samples are taken at three defined sampling taps corresponding to specified contact times (tap 1: 25 sec, tap 2: 10 min, and tap 3: 25 min), the samples are neutralized to stop the action of the disinfectant, and the concentrations of the test microorganisms are determined. The reductions obtained for each of the test microorganisms are calculated. According to the UBA method, two replicates (with 3 measurements of each contact time) of each test must be carried out, and with the average of the results of the same, determine if the substance or test product presents bactericidal and/or viricidal activity.
According to the UBA method, a substance or test product possesses bactericidal activity when it reduces the concentration of bacterial cells of the Escherichia coli and Enterococcus faecium strains by at least 2 log after a contact time of 10 minutes, and at least 4 log after 25 minutes. A substance or test product possesses viricidal activity when it reduces the concentration of bacteriophages MS2 and PRD1 by at least 2 log after a contact time of 10 minutes, and at least 4 log after 25 minutes.
The concentration of the test substance or product in the sampling taps must also be determined, to measure the loss of the disinfectant, with respect to the added concentration. A prerequisite indicated by the UBA method for the determination of bactericidal or viricidal effects is that the substance to be analysed is quantitatively measured at reasonable costs and that its effect can be neutralized in a short period of time. Before submitting a product for testing, you must verify that the laboratory has the equipment for the measurement of the test substance or product that you want to analyse.