To what extent is it permissible to mix sewage water with groundwater in what is known as a cesspit?

The question pertains to three issues:

1. The effect of impure wastewater on groundwater: Well water is originally pure and becomes impure if it changes due to mixing with impure wastewater. However, if the change is due to proximity and not mixing, it remains pure.

2. The ruling on irrigating crops with impure wastewater: The majority of scholars do not forbid this and rule that the crops are pure and permissible to eat, contrary to the Hanbalis who consider them impure and forbidden to eat until they are irrigated with pure water.

3. The health and environmental impact of this action: This should be referred to specialists. If they prove its harm and danger, then it is ruled to be prohibited to remove the harm, in accordance with the Prophet's (PBUH) saying: "There should be neither harming nor reciprocating harm." Indeed, Islamic law came to remove and prevent any harm proven by Sharia.