Using wood from the few pallets of aid that make it into Gaza, and window panes salvaged from buildings that have largely been abandoned in 10 months of war, the 50-year-old agricultural engineer built a glass-covered trough.
She lets saltwater evaporate from the trough, heated by the greenhouse effect created by the glass panes, allowing the water to distil and leaving behind the salt.
From there, a long black hose carries the evaporated water to other containers filled with activated charcoal to further filter out impurities.
"It is a very simple device, it's very simple to use and to build," Ghul told AFP after taking a long gulp from a glass of filtered water in her house in Khan Yunis, in the southern Gaza Strip.
Abundant energy
Ghul's device "doesn't require electricity, filters, or solar panels, it operates solely on solar energy", which Gaza has in abundance, with 14 hours of sunshine per day in the summer, and eight hours in the winter.
This has proven particularly useful at a time when Gaza's only power plant is down and electricity supplies from Israel have been cut for months.
With fuel also in short supply, Gaza's desalination plants that haven't been damaged in the fighting have been working at a drastically reduced capacity.
Mohammad Abu Daoud, a displaced Gazan sweating in the midday sun, said Ghul's invention "comes exactly at the right time".
"For about two months, we have relied on it entirely," he told AFPTV.
This brings crucial help to those who benefit from it, as the available water for Gazans currently averages 4.74 litres per day, "under a third of the recommended minimum in emergencies", Oxfam reported in July.
This represents "less than a single toilet flush", the aid group warned in a report, which estimates that available water per person per day in the Gaza Strip plummeted by 94 percent since the beginning of the war.
Water was already scarce before the conflict erupted, and most of it was undrinkable. The 2.4 million population relies primarily on an increasingly polluted and depleted aquifer, humanitarian agencies say.
'Water as a weapon of war'
The war broke out with Hamas's October 7 attack on Israel, which resulted in the deaths of 1,199 people, mostly civilians, according to an AFP tally of Israeli official figures.
Israel's retaliatory offensive in Gaza has killed at least 40,173 people, according to the territory's health ministry, which does not provide a breakdown of civilian and militant deaths.
In the school-turned-shelter where Abu Daoud lives, close to Ghul's house, other displaced families have come to rely on the water filtration system to fill up their bottles.
The 250-litre tank that stores the clean water quickly empties.
Oxfam accuses Israel of using "water as a weapon of war", and has warned of "a deadly health catastrophe" for Gazans, almost all of whom have been displaced at least once.
The aid group calculated that "Israeli military attacks have damaged or destroyed five water and sanitation infrastructure sites every three days since the start of the war".
The lack of clean water has had drastic effects on the population, with "26 percent of Gaza's population falling severely ill from easily preventable diseases", it said.
Conscious of the pressing need for her device and of the ubiquitous danger of air strikes, Ghul regularly climbs up to her terrace to watch over her creation, and to open or close her precious taps.
