Groundwater - found below the ground where it accumulated in between soil and rocks. The volume of water can range from small to very large similar to above ground creeks, rivers and lakes.
Most countries, including Canada, have set an aesthetic rather than a health guideline for manganese. The reason for this is that levels above the guideline can stain porcelain and laundry, drinks such as coffee and tea can become cloudy and taste funny. High manganese levels can also cause diarrhea.