Legionella in thermostatic shower valves an exploratory field study

1. Legionella in thermostatic shower valvesan exploratory field study J. Van Hoof (ISSO) L.M. Hornstra (KWR) O.W.W. Nuijten (ISSO) P.W.J.J. van der Wielen (KWR) W.G. van der Schee (TVVL) E. Van der Blom (Uneto-VNI)

2. Why this study? High-Priority-installations require routine analysis on legionella Even with regular analysis contamination is frequently reported • High numbers of legionella are reportedthermostatic shower valves (TSV’s) • Contaminations appears often persistent Objective of the study: • Investigate TSV’s in the field on legionella • Determine if TSV’s cause the growth of legionella by themselves 14002

3. Approach First step: Select locations with a persistent legionella history during the last two years. The field study consisted of: • Sampling the water of the TSV on three places • Demounting the TSV for research in the laboratory • Sampling the hot and cold water supply • Measure the temperature of the hot and cold water supply • Fill in a questionnaire with data on the: • Ambient temperature • Frequency of use of the TSV • Water installation (history, maintenance) 14002

4. Investigation of the TSV Cross section type A 1. Outlet shower hose (not visible) 2. Cold water inlet 3. Mixing chamber 5. Mix water outlet 4. Hot water inlet 6. Rubbers and other parts 14002

5. Investigation of the TSV Cross section type B 4. Hot water inlet 6. Rubbers and other parts 14002

6. Autopsy Demounting of a TSV prior to taking the swab samples 14002

7. Autopsy 14002

8. Sampling of the water The TSV outlet mixed water • Tap and water samples • Analyse on Legionella • According NEN 6265:2007 • Inlet warm only < 55 °C Inlet cold Inlet warm 14002

9. Investigation September 2012 until May 2013 at 5 locations Total 10 TSV’s were sampled 14002

10. Legionella (cfu/l) 14002

11. Legionella (cfu/l) 14002

12. Legionella (cfu/l) 14002

13. Legionella (cfu/l) 14002

14. Legionella (cfu/l) TSV cold TSV False negative 14002

15. Legionella in the TSV (cfu/l) 5 TSV’s: collective swab; 5 TSV’s: separate swab SwabTSV 2TSV 6 1 exit chamber shower hose Inlet warm 2 Inlet cold Inlet cold 1 3 Mixing chamber Inlet cold 2 4 Inlet warm Exit chamber of shower 5 outlet Mixing chamber 6 Rubbers en other parts Rubbers en other parts Highest number on rubber (smallest surface) Second highest number on inlet cold 14002

16. Rubber, biofilm and Legionella Rubber enhances the growth of bacteria. Rubber: • encourages high concentrations of biofilm on the surface • is probably a “hotspot” for legionella 14002

17. Conclusions • Legionella can settle inside TSV’s • TSV’s can play a role in exceeding the threshold limit (100 cfu/l) • The highest number of legionella was observed on rubber parts • Legionella was found inside two TSV’s, but not in water coming from the tap. Legionella stays in the biofilm • At 50% of the cases legionella was found in cold water • At 50% of the cases the warm water supply did not exceed 55 °C • The control for legionella in water systems can be improved 14002

18. Recommendations • Design TSV’s without material that encourages the growth of bacteria (rubber) • Identify exactly the influence from the shower hose in further research 14002

19. Legionella in thermostatic shower valvesan exploratory field study J. Van Hoof (ISSO) L.M. Hornstra (KWR) O.W.W. Nuijten (ISSO) P.W.J.J. van der Wielen (KWR) W.G. van der Schee (TVVL) E. Van der Blom (Uneto-VNI)