Laboratory testing of the susceptibility to crevice corrosion for pipe/connection systems based on break-through potentials in simulated drinking water (demineralised water + chloride) indicates that it is safe to use 1.4401 connections in the temperature range 20-65 °C [8]. However, these data were not obtained in natural drinking water and test duration is usually short. The corrosion attacks in low chloride water have been linked to microbial activity, and it does cause concern regarding the wide application of stainless steel and the general recommendation for Danish water systems. If we were able to understand the mechanism and the conditions needed for MIC to develop in these systems, these corrosion attacks might be predicted and prevented. For the industry this will mean a higher success rate in choosing the right material for an installation and less costs and disturbance for the consumer.