In the besieged Gaza Strip, 2.3 million people do not have access to clean running water because of Israel’s decision to cut off water and electricity to the enclave while pounding it with air strikes.

Israel’s chokehold has seen taps run dry across the territory.

When water does trickle from pipes, it lasts no more than 30 minutes each day and is so contaminated with sewage and sea water that it is undrinkable, residents say.

The deprivation has plunged Gaza’s population deeper into misery as Israel’s bombardment intensifies one week after Hamas fighters surged across Israel’s separation fence, killing 1,300 Israelis and abducting dozens.

“I don’t know what we’re going to do tomorrow,” 65-year-old Abu Samhadaneh said from her three-room home in the southern town of Rafah, which turned into a de facto shelter after Israel demanded everyone in Gaza evacuate south.

She said she rations just a few litres among dozens of friends and relatives each day, adding: “We’re going crazy.”

Israel’s retaliatory strikes have crushed hundreds of buildings in Gaza and killed more than 2,200 Palestinians.

Even as terrified families flee their homes – squeezing into United Nations shelters or the bloody and chaotic halls of Gaza’s biggest hospital in fear for their safety – the desperate search for water remains a constant.

UN agencies and aid groups are beseeching Israel to permit emergency deliveries of fuel and other supplies into the Gaza Strip.

“There really can’t be a justification for this kind of targeting of civilians,” said Miriam Marmur, a spokesperson for Gisha, an Israeli human rights group.

The UN Palestinian refugee agency called the water crisis a “matter of life or death”.

If fuel and water do not arrive soon, the agency’s commissioner general Philippe Lazzarini said, “people will start dying of severe dehydration”.

In normal times, the coastal enclave – which has struggled under an Israeli-Egyptian blockade since Hamas seized control of Gaza in 2007 – relies on Israel for one-third of all available drinking water, the territory’s water authority says.

Its other water sources include desalination plants in the Mediterranean Sea and a subterranean aquifer, drained and damaged from years of overuse.

When Israel severed electricity to Gaza, the desalination plants all shut down. So did the waste water treatment stations.

That has left the entire territory without running water. People buy dwindling jugs from municipal sanitation stations, scour for bottles in supermarkets or drink whatever liquid may dribble out of their pipes.

Quenching thirst has become more difficult in the past day, even for those with means to shell out for bottled water.

It took 35-year-old Noor Swirki two hours on Saturday to find a box of six bottles she will try to stretch throughout the coming days.

She took her first shower in a week on Saturday, using a cup of polluted tap water and splashing it over her husband and two children before rubbing the remaining moisture on her skin.

“We are here without anything, even the most basic thing,” she said, shouting over the persistent noise of crying children in the UN shelter in southern Khan Younis, where she sought refuge after an airstrike demolished her Gaza City apartment.

“We’re worried about our safety in the bombing and now there’s this other issue of survival.”

She and six other Palestinians interviewed across Gaza said they drink no more than half a litre of water a day. They said they urinate once a day or every other day.

The World Health Organisation says that 50 to 100 litres per day per person are needed to ensure proper hydration and sanitation.

The US National Academies of Science and Medicine say men need to drink about 3.7 litres (125 ounces) and women need about 2.7 litres (91 ounces) per day to be adequately hydrated.

“It’s like we’re in the stone ages,” said 28-year-old Khalil Abu Yahia in the central town of Deir al-Balah.

Drinking dirty water and poor sanitation due to lack of water can lead to terrible diseases, experts say, including cholera, dysentery, typhoid and polio. For the past week, the water along Gaza’s coast tasted like salt, residents say.

Drinking salt water can lead to even more dehydration.

Among the dozens of Palestinians with shrapnel wounds in their legs and arms from air strikes that Dr Husom Safiyah treated on Saturday in northern Gaza, there were 15 children, including infants, with bacterial dysentery caused by the water shortage, he said.

“The situation is disastrous, and it will become even more so after two or three days,” said Dr Safiyah, a physician with MedGlobal, an organisation that sends medical teams to disaster regions.