Five-year-old Tala Ibrahim Muhammad al-Jalat is just about awake but not moving, her milky eyes rolled to the back of her head.

Tala is severely dehydrated and malnourished.

By her bedside in Nasser hospital in Khan Younis her father Ibrahim Muhmmad al-Jalat holds her hand, careful not to disturb the intravenous drip feeding into her wrist.

He knows that the scorching weather, with temperatures close to 40 degrees, and a lack of clean water have brought his daughter close to death.

"The situation is getting worse," he says.

"The temperature in our tent is unimaginable, and the water we drink is definitely contaminated, because both young and old are getting sick."

With their homes destroyed, hundreds of thousands of Gazans are now displaced, living under canvas in makeshift camps with little protection from the scorching sun.

Getting water, whether it is clean or not, is a daily struggle. Long queues form at distribution centres.

With the sewage system badly damaged and with few toilets, what water there is is easily contaminated.

"It is no secret that the biggest cause of intestinal infections currently occurring in the Gaza Strip is the contamination of the water supplied to these children," says Dr Ahmed al-Fari, head of the children's departments at Nasser Hospital.

"The first problem is intestinal infections with vomiting and diarrhoea which causes dehydration," he says.

"The second problem is hepatitis C or A, which are no less dangerous than intestinal infections, if not more so."

The United Nations Office for the Co-ordination of Humanitarian Affairs says 67% of Gaza's water and sanitation system, poor at the best of times, has now been destroyed.

"We need a tremendous international effort to re-establish water and sewage networks," says Salaam Sharab, who's a water engineer in the Khan Younis municipality.

"We in Khan Younis have lost between 170 and 200km of pipes, which have been completely destroyed, along with wells and water tanks."

The Israeli military says it is allowing around 200 trucks carrying humanitarian aid to enter the strip through the Kerem Shalom crossing every day.

It says the problem is that aid agencies on the other side are not distributing it.

The aid agencies argue continued fighting, especially in the area around Rafah in southern Gaza, means it is too dangerous for them to operate.

They also say what's being allowed in is a drop in the ocean of what's actually needed.

Children with pre-existing conditions can be especially hard hit by malnutrition and contaminated water.

Lying semi-conscious on a bed further down the corridor from Tala is nine-year-old Yunis Jumaa, who has cerebral palsy.

His mother Ghanima says eight months of war have dramatically worsened his health.

"When he developed this malnutrition and dehydration, he became as you see him now," she says.

"There is no bottled water. The children walk a long distance - when they get water it reaches us contaminated," she adds.

Gazans' growing desperation to get food and water means there is also a threat of looting with reports of aid trucks being ransacked by gunmen as well as by ordinary civilians.

But the International Criminal Court prosecutor has accused Israel of using starvation as a weapon of war and has requested arrest warrants for the Prime Minister Benjamin Netanyahu as well as the Defence Minister Yoav Gallant.

The Israeli government has reacted with outrage at the move.

It insists that claims by aid agencies that there is already widespread famine in Gaza are exaggerated and says it is Hamas which started the war, bringing suffering and misery to Palestinians.

The United Nations has warned that more than a million Gazans face the highest level of starvation by the middle of July.

Israeli ministers deny there is a humanitarian crisis in Gaza.

But for Ibrahim Muhmmad al-Jalat and Ghanima Jumaa at their children's bedsides in Nasser hospital, it doesn't feel that way.