Dozens of Palestinian villages have to bring water by lorry as it is not piped in
Israeli human rights group B'Tselem says the West Bank is facing grave water shortages largely because Israel's "discriminatory" policies.
The group criticises the distribution of joint water resources and limits placed by Israel on the Palestinian Authority's ability to drill new wells.
"It will have serious repercussions on the economy and health," B'Tselem said.
West Bank per capita water use is about 66 litres a day - just two-thirds of the recommended international minimum.
The accumulated effects of a series of dry years would make matters worse in the months to come, the group added.
Per capita water consumption by Israeli settlers in the West Bank is 3.5 times that of Palestinians, B'Tselem says.
Water consumption per head of the population is calculated by including the consumption of livestock.
In some parts of the northern West Bank, a largely agricultural area, consumption is far below the overall average, B'Tselem says.
"The chronic water shortage results in large part from Israel's discriminatory policy in distributing the joint water resources in the West Bank and the limits it places on the Palestinian Authority's ability to drill new wells," its statement says.
A recent United Nations report highlighted water shortages in the Gaza Strip, and said a lack of spare parts and fuel meant sewage plants could not function properly.
The Israeli military administration in the West Bank had no immediate comment about the B'Tselem report.
A spokesman for Israel's water supplier told Jerusalem Post that it provided 500 million cubic meters per year, which is 30% more than required under peace accords signed in the mid-1990s.
He said Israel was facing water cutbacks and severe shortage itself but continued to increase supply to Palestinians in the West Bank.