Refill NZ has Wellington businesses signed up to provide free water bottle refills - free of charge.

With a month of remarkably hot weather on the way, cafes are being called on to refill water bottles for free.

RefillNZ co-founder Owain John said Kiwis were often shy about approaching cafes for free water.

"There's a little bit of a social awkwardness because you're going in to somewhere asking for something for free."

SUPPLIED RefillNZ say they want to reduce the amount of plastic bottles littering the environment.

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Drinking fountains could be old and hard to use, but businesses already had the means to provide free water at no cost, he said.

"What we're doing is putting in more water fountains without making more infrastructure."

AMBER-LEIGH WOOLF/STUFF RefillNZ co-founders Owain John and Jill Ford say water refills should be free, saving the environment from bottles, and saving people money too.

RefillNZ co-founder Jill Ford said, with summer approaching and cruise ship season near, having cafes refill water bottles could cut down on litter by making people less likely to buy a new plastic water bottle.

About 526 million water bottles are thrown away in New Zealand each year, and just one third of them are recycled

So far, about 40 Wellington businesses have said yes to offering free water bottle refills. Those who are on board display a sticker in their window.

AMBER-LEIGH WOOLF/STUFF Each cafe in Wellington that agrees to refill water bottles for free displays a sticker - 40 cafes have said yes so far.

In Upper Hutt, the city council said it had been working with local cafes and bakeries to set up a scheme where reusable drink bottles are refilled for free, provided the bottles are clean and paying customers have priority.

A blue window sticker with "BYOB" (bring your own bottle) will be displayed at participating cafes and bakeries.

A recent study published in New Zealand Medical Journal found only 20 per cent of playgrounds surveyed had a functioning water fountain.

This year, more drinking fountains were rolled out at Taranaki playgrounds in a bid to combat the region's high child obesity rate.

Wellington City Council open space and parks manager Myfanwy Emeny said drinking fountains were installed in all new playgrounds.

"We are adding three new fountains to the waterfront, and as part of our healthy living plan we also have water available in as many practicable situations as possible – i.e. sports grounds and pavilions."