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A setup for potentiostatic testing of eight specimens at different potentials in a common electrolyte pool was developed. The potentiostat requires only one reference electrode and one counter electrode to control all working electrodes and its design is easily scalable with respect to the number of channels. The system is applied to assess the effect of chloride, sulfate, and bicarbonate in fresh water‐typical concentration on a nickel‐aluminum bronze, assuming some anodic polarization by stainless steel with and without microbially induced ennoblement. Chloride and sulfate activate corrosion, bicarbonate has a passivating effect, and its combination with chloride and sulfate promotes localized corrosion. The susceptibility of nickel‐aluminum bronze to localized corrosion may be high in fresh water when polarized anodically. Potentiostatic corrosion testing may yield practically relevant results for systems with slow kinetics.

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Pipes made of stainless steel in the drinking water supply system showed pitting corrosion in the heat-affected zone (HAZ) of the welded joints. This was very surprising considering the chemical composition of the fresh water and the fact that no microbiologically influenced corrosion (MIC) had been found.Testing for pitting corrosion showed no increased sensitivity of the HAZ. The Electrochemical Potentiodynamic Reactivation test (EPR test), however, was positive for the tube interior and only within the HAZ. Metallographic examinations were carried out to clarify if sensitization or intergranular attack, a type of corrosion, were the cause.The holes showed an irregular propagation which can be explained by segregation lines in the steel. It is noticeable that the holes preferably propagate in the mid-thickness region of the steel sheet. The metallographic samples showed no preferred corrosive attack along the grain boundaries (intergranular attack) and also no sensitization of the steel.