cted against contamination due to such factors as depth of the well and the type of soil and the integrity of the well casing.(v) Elevated nitrate levels at the water supply source.(vi) Use of PCBs in equipment used in the production, storage, or distribution of water (i.e., PCBs used in pumps, transformers, etc.).(7) If an organic contaminant listed in ??141.61(c) is detected (as defined by parag