Millions displaced by conflicts have found refuge in water-stressed countries, where their perceived effect on water availability has shaped local water security discourses. We leverage new annual global data on the water footprint of food production to elucidate the effects of refugee displacement on host countries' water stress. The blue water demand transferred by refugees has nearly doubled between 2005 and 2016. It tends to be transferred towards countries with less water-intensive food provision systems, but more water-intensive dietary habits and comparably scarce water resources. Although minimal in most countries, implications on water stress can be dramatic in vulnerable countries that are already at risk of severe water crises. The 3.3 million refugees in Jordan may have contributed to water stress by up to 60%-points. We find that small changes to current UNHCR refugee resettlement goals can substantially ease the effect of refugee displacement on water stress in vulnerable countries.