Legionella in thermostatic shower valves an 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)

High-Priority-installations require routine analysis on legionella Even with regular analysis contamination is frequently reported High numbers of legionella are reported thermostatic 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 Why this study?

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: o Ambient temperature o Frequency of use of the TSV o Water installation (history, maintenance)

Investigation of the TSV Cross section type A Outlet shower hose (not visible) 2. Cold water inlet 4. Hot water inlet 5. Mix water outlet3. Mixing chamber 6. Rubbers and other parts

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

Autopsy Demounting of a TSV prior to taking the swab samples

Autopsy

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

Investigation September 2012 until May 2013 at 5 locations Total 10 TSV’s were sampled 9 TSV numberLocationLegionella history 11 HotelYes 21 HotelYes 32 HotelNo 43 HealthYes 53 HealthYes 64 HealthYes 74 HealthYes 84 HealthYes 95 HealthYes 105 HealthYes 14002

Legionella (cfu/l) 10 TSV number LocationTSV mixTSV coldTSV warmAutopsy 11 Hotel Hotel- 43 Health Health Health- 95 Health Health

Legionella (cfu/l) 11 TSV number Location TSV mixTSV coldTSV warm Autopsy 11 Hotel Hotel Hotel Health Health Health Health Health Health

Legionella (cfu/l) 12 TSV number Location TSV mixTSV coldTSV warm Autopsy 1 1 Hotel > 55 °C 2 1 Hotel1.400-> 55 °C 3 2 Hotel--> 55 °C 4 3 Health Health-330> 55 °C 7 4 Health1.800-> 55 °C 8 4 Health Health Health

Legionella (cfu/l) 13 TSV number Location TSV mixTSV coldTSV warm Autopsy 1 1 Hotel > 55 °C- 2 1 Hotel1.400-> 55 °C+ 3 2 Hotel--> 55 °C- 4 3 Health Health-330> 55 °C+ 7 4 Health1.800-> 55 °C+ 8 4 Health Health Health

Legionella (cfu/l) 14 TSV number Location TSV mixTSV coldTSV warm Autopsy 1 1 Hotel > 55 °C- 2 1 Hotel1.400-> 55 °C+ 3 2 Hotel--> 55 °C- 4 3 Health Health-330> 55 °C+ 7 4 Health > 55 °C+ 8 4 Health Health Health TSVTSV cold False negative 14002

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

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

Conclusions 17 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

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

Legionella in thermostatic shower valves an 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)