STORY: The Greek Island of Naxos' biggest reservoir has been sucked dry.

And with the country's islands set to flood with a record number of summer tourists, the strain on water supplies has rarely been heavier, officials, farmers and scientists say.

Naxos is a mountainous island with a population of just 20,000 but its beauty and weather attract tens of thousands of visitors each day over the peak season.

The prospect has hotel owners like Vangelis Katsaras on edge.

"In recent years there has been a problem with water shortages, and this year in particular we are experiencing it more intensely."

Most of Greece has seen little or no rain in months, with the impact of climate change bringing higher temperatures, erratic rainfall and wildfires.

The island's two reservoirs currently hold a third of last year's levels, the equivalent of just a few dozen Olympic swimming pools.

Three portable desalination units have been secured to treat sea water to make it safe to drink.

Mayor Dimitris Lianos says that should cover the shortfall for houses, hotels and pools.

''We believe there will be some problems, not daily, but in some areas, some higher regions. But we believe there will not be serious problems such as water cuts in villages. We believe things will go well and that is why we took all these measures."

Other industries, though, won't be so fortunate.

Farmers won't receive any of the treated water and will have to rely on wells contaminated by sea water aquifers.

They say this contamination happens when the wells are empty enough for the salty water to creep in.

It threatens Naxos' famous potatoes grown by farmers like Stelios Vathrakokoilis who says the use of salty irrigation water will halve his yields.

''It's a big disappointment. We humans did not succeed in foreseeing that climate change was going to knock on our doors as well as the rest of the world, and if this continues, may the Virgin Mary help us, that is all I can say."

Countries across the Mediterranean are looking for ways to back up their water supplies by using desalination.

But suppliers say units were in short supply this summer due to soaring demand.

And climate experts fear the worst is yet to come, saying once the effects of drought become visible, it is too late to take action.