For microorganisms, the preferred living state is adhering to surfaces that can lead to
the development of a biofilm. In drinking water networks, a biofilm can affect the
organoleptic quality of the water as well as whether it is safe to drink. This is due to
the probable presence of pathogens inside the biofilm which may be spread in the water. To
keep the water quality safe, sanitization processes are regularly carried out using
oxidizing biocides which can alter the physico-chemical properties of the material. Due to
their surface physico-chemical properties and their high corrosion resistance, stainless
steels seem to be good candidates for the making of drinking water systems. In this 2 year
study, stainless steel grades were compared with materials commonly used, in respect of
fouling, biofilm development and composition. The tested stainless steels include ferritic
(444/EN 1.4521), three austenitic (304L/EN 1.4307, 316L/EN 1.4404, and 316LN/EN 1.4429)
and two duplex (2304 /EN 1.4362, and 2205/EN 1.4462) grades. The experiments were
performed in a pilot specially designed to assess the material biocontamination on a
natural drinking water loop for more than 2 years. The results confirmed the significant
impact of the material on the biofilm development in terms of formation kinetic and
ecology. No differences were observed between stainless steel grades whereas they
displayed an intermediate behaviour compared to other materials. Corrosion attacks were
only observed on galvanised carbon steel while on stainless steels, negligible release
rates, much below international health requirements were measured. So stainless steels
offer a good compromise to make drinking water pipes.