The UN has urged Israel to allow 150,000 tents into flood-hit Gaza.
Israel maintains Hamas has been stealing aid and using it for its own purposes.
The flooding is the result of the first heavy rains of what will be a long and wet winter.
Palestinians in Gaza are desperately trying to find new ways to prop up flimsy tents and shelters ahead of the long and wet winter, pulling material out of destroyed buildings to reinforce tarpaulins and sheeting.
Last weekend, the first heavy rains of the season hit the war-ravaged strip, flooding the sprawling tent camps where hundreds of thousands of people live.
A woman and three children were killed by a collapsing sand bank, according to local health authorities.
The United Nations said more than 40,000 tents had been damaged, leaving more than 200,000 people without safe and dry accommodation.
In many instances, floodwaters had mixed with sewage, with much of Gaza's infrastructure destroyed during the war, fuelling concerns of fresh outbreaks of diseases in the overcrowded ramshackle communities.
Sharif Abu Shaar, 45, was among the Palestinians sourcing material like reinforcement bars from damaged buildings in Khan Younis, in an attempt to strengthen existing shelters against storms.
"We lived in miserable conditions, with water, wind and rain. It was a catastrophe," he told the ABC.
