Any extractive industry causes some harm to the environment. Modern society is entirely dependant upon these industries-without them life would become very harsh for the survivors.
Hopefully some lessons have been learnt over time. The mining disaster of Abervan was a catastrophe that could and should have been avoided.
Today there is some attempt to quantify risk by way of environmental impact statements. Not a perfect solution but a step in the right direction.
Personally I would have no problem with fracking if indenpendant auditors monitor the process at all stages. This is common for landfill cell construction.
The techniques for fracking are not vastly different to those employed for oil or gas wells. The major problem would appear to be departures from the original planning submission on the grounds of expediency.
Independant monitoring would prevent this from happening.
Issues of water source contamination would seem superficially to be due to lack of casing integrity, and there are a variety of ways of checking this.