Children under five who live in conflict zones are 20 times more likely to die from diarrhoeal diseases linked to unsafe water than from direct violence as a result of war, Unicef has found.

Analysing mortality data from 16 countries beset by long-term conflict – including Afghanistan, Iraq, Syria and Yemen – the UN children’s agency also found that unsafe water, sanitation and hygiene kills nearly three times more children under 15 than war.

Unicef’s executive director, Henrietta Fore, said the findings, published in a report published on Friday to mark World Water Day, underline the need for access to safe water and sanitation to be treated as a human right rather than a privilege.

“Deliberate attacks on water and sanitation are attacks on vulnerable children,” said Fore.

“The reality is that there are more children who die from lack of access to safe water than by bullets. Water is a basic right. It is a necessity for life.”

The report compared World Health Organization data on “collective violence” and “diarrhoeal disease” from 2014 to 2016 in Afghanistan, Burkina Faso, Cameroon, Central African Republic, Chad, the Democratic Republic of the Congo, Ethiopia, Iraq, Libya, Mali, Myanmar, Somalia, South Sudan, Sudan, Syria and Yemen.

Diarrhoeal disease linked to unsafe water, sanitation and hygiene kills an average of 72,000 children under five each year, while direct violence from war kills an average of 3,400, according to the report.

Diarrhoea killed more children under five in each of the 16 countries analysed bar Libya and Syria, the report found. Under-15s were more likely to die from diseases related to unsafe water everywhere but Libya, Iraq and Syria.

“Human beings can run away or take shelter from bullets or bombs, but they will run towards and seek out water at any cost,” said Omar El Hattab, Unicef’s regional chief of water, environment and sanitation for the Middle East and North Africa.

“Unfortunately, unsafe water, sanitation and hygiene reaches every household, and will still be demanded by people – if people are thirsty, they will drink any kind of water. In Yemen, a child dies every 10 minutes from preventable causes, and many of those causes – malnutrition, cholera, diarrhoea – are related to unsafe water, sanitation and hygiene.”

Lack of access to adequate water and sanitation adversely affects girls more than boys, making them vulnerable to sexual violence as they collect water or use latrines, said the report.

Children forced to flee their homes because of the Boko Haram insurgency drink water in a school yard in Bol, in Chad’s Lake region. Photograph: Vlad Sokhin/Unicef

Yet the changing nature of conflict means that water, sanitation and hygiene systems are often targeted as a means of attacking civilians, which is in breach of the Geneva convention, said Sian White, of the London School of Hygiene and Tropical Medicine.

“Hospitals and water and sanitation infrastructure used to be ‘off limits’, with warring parties respecting their value to human life, but recent experience indicates that this is no longer the case,” said White.

“Perpetrators of conflict are increasingly viewing water and sanitation systems as an asset of war that can be harnessed to gain power and destroyed to inflict harm on civilians.”

The bombing of a water production plant in Hodeida last July deprived more than 1 million people of drinking water, said El Hattab. Fighting in Syria has also resulted in key water, sanitation and electricity systems being repeatedly damaged since conflict broke out in 2011, with deliberate shutdowns affecting as many as 2 million people at a time, said the report.

“Water, sanitation and hygiene services should never be interrupted or politicised: access to safe water is a human right, not a privilege,” said El Hattab.

“Indiscriminate attacks on water and sanitation services must be stopped, and personnel for power supply, and water and sanitation workers should be allowed to access facilities for repairs and maintenance irrespective of where those facilities exist.”