Given these two herbicides:
Product A: kills by poisoning the soil, is highly solvent in water, is highly mobile in wet soil, is highly prone to runoff impact on surface water and streams, and never breaks down in the environment. Requires a highly concentrated application to be effective.
Product B: Kills via contact with green plant tissue, is highly solvent in water, but has low soil mobility, is broken down in runoff water by sediment particles, and has a half life of 30-60 days in soil. A 1% solution is all you need to kill most target plants.
It is amazing to me that one would consider product A to be the safer choice to use near a source for well water.
H