Most of the largest canals have at least one deep well dug to the depth of ground water.
For many aquatic insects they are refuges from terrestrial existence in areas where there is little ground water available.
Furthermore, intrusion of sea water in the ground water and changes in temperature can reduce agricultural incomes.
In swimming lakes dilution effects and water exchange with ground water quickly reduce infection risks to co-bathers following a point contamination.
Over time, unburned fuel contaminated the ground water aquifer.
Ground water is often distributed without any treatment.
The river is highly polluted, with adverse effects on the ground water in the locality.
The evidence from the raw data therefore points overwhelmingly in favour of piped water supplies as being less contaminated than ground water supplies.
