Sulphur and occasionally also high amounts of manganese as well as small amounts of phosphorous were detected in the deposits in or around the pits by energy dispersive spectroscopy (EDS). This indicates that manganese probably exist as MnO2 (a compound formed by aerobic bacteria) and S as a sulphide formed by the reduction SO4--. SRB and a high amount of aerobic bacteria (4.3 *106 cfu/ml) could be detected in a sample that was delivered moist to the laboratory and cultivated in microbiological assays. The samples for microbiological analysis had wall-through pits. The presence of IOB was verified in one pipe sample and in the water, but the presence of MOB was not checked.