Survey of the microbiological quality of drinking water supply in hospitals. Drinking water cooler vs tap water fed dispenser vs bottled water

Abstract number: 1134_02_320

Adler S., Eikenberg M., Mlangeni D., Daschner F.D.

Objectives:

Hygienic, economic and ecologic comparison of drinking water coolers versus tap (mains) water-fed dispensers versus bottled drinking water.

Methods:

Samples were taken from each system without preflow or cleaning of the nozzle. These comprised 2 samples from 20 drinking water coolers each over 2 months, 1 sample per week from the tap water dispenser over 6 months, and samples from 6 different bottles of drinking water. Total colony counts were analysed at 22°C and 36°C, respectively. Total P. aeruginosa, E. coli, and coliforms, as well as sulphite-reducing clostridia were examined according to European Norms (EN ISO) for compliance with the German Drinking Water Ordinance 2001 (limit value for total colony counts at 22 ± 2°C: 100 cfu/ml, at 36 ± 1°C: 100 cfu/ml and 20 cfu/ml for bottled water). Costs per litre were calculated and compared based on the economic data supplied by the manufacturers. The ecological impact of the different systems was evaluated based on expert opinion.

Results:

All the samples from the water cooler system exceeded German Drinking Water Ordinance threshold values. All the samples taken from the tap water dispenser, and, with one exception, all the samples from the bottled water complied with the German Drinking Water Ordinance. If more than 400 l of water are consumed per month, the tap water dispensing system and bottled water are more economical than the water cooler system ([euro] 0.57 per l for water cooler, [euro] 0.45 for month tap water dispenser, [euro] 0.49 per l for bottled water). In economic terms, the water cooler system can only be recommended for consumption levels below 400 l per month. From an ecological point of view, the tap water dispenser is most favourable (expressed in CO2-emissions per year for 403.720 l at Freiburg University Hospital), followed by the water cooler system and finally the bottled water.

Conclusion:

For reasons of hygiene, the use of water cooler systems cannot be recommended in hospitals. Furthermore, drinking water cooling systems are only economic for low consumption rates. Tap (mains) water-fed dispensers feature the best hygienic, economic and ecologic properties.