Certainly, although methane gas dissolving into drinking water certainly carries it's own risks. Those risks are more explosion and oxygen displacement, since AFAICT once coming through a faucet or whatever it should separate from the water (it is a gas).

Oil contamination will ruin a potable water supply for a long time to come, it will mix with the water and make it unusable for human, animal or plant consumption - outside of a complete drainage and refilling of the water table (hah, good one) it's just going to continue to be more and more diluted but still present until a very long period of time has passed.

This is the major fear of these pipelines, any leak could potentially do irreparable harm (in a human time frame) to a water supply - and oil pipelines have leaked before, we haven't suddenly got some new engineering magic to stop it.