B'tselem
'Wastewater in the West Bank – from the settlements, from parts of Jerusalem, and from Palestinian communities – amounts to 91 million cubic meters [mcm] a year. Most of it is not treated, despite the sanitary and environmental danger inherent to wastewater flowing freely. Prolonged neglect of this issue has caused severe hazards in the West Bank and is liable to pollute the Mountain Aquifer, the most important and highest-quality water source for both Israelis and Palestinians...
During more than 40 years of occupation, Israel has not built advanced regional wastewater treatment plants in the settlements to match those inside Israel.
... Since settlers in the West Bank use Israel’s water-supply system, neglect of wastewater treatment in the area has almost no effect on them. Palestinians, however, ... rely on water from natural sources...pollution of these sources aggravates the chronic drinking-water shortage in the West Bank...use of untreated wastewater for agriculture contaminates crops and harms a major sector of the Palestinian economy. In the long run, the flow of untreated wastewater will also diminish land fertility... Full story