They had their heyday in the Twenties and Thirties, but many have since fallen into disrepair. Today committed volunteers have helped reopen a number of lidos.

Sipping a long cool drink after a refreshing dip in the pool. What could be nicer on a warm summer's day?

With Britain sweltering in a heatwave, more and more people are turning to our once-forgotten lidos.

Fashionable early last century, the outdoor municipal pools went out of style as more swimmers turned to indoor baths which could stay open all year round.

Many were used for other things, such as Worthing Lido, which is now a family entertainment centre.

Others, such as Saltdean Lido near Brighton, gradually fell into disrepair.

But today, the innovative art deco amenity, built in 1935, is thriving once more after a £2 million refit in 1998.

When The Argus popped by this week, youngsters were splashing around while mums and dads were topping up their tans and drinking the cafe out of tea.

Manager Tony Sarin said: "Believe it or not, the demand for hot drinks never stops."

Staff were also doing a roaring trade in burgers and chips, as well as cool drinks and ice creams.

Mr Sarin said: "The pool is only open for four months of the year, weather permitting. We have to make enough money over these four to sustain us for the next 12. At the moment business is booming.

"On a sunny day we will get up to 600 people coming along but we can cope with more. We just bring more lifeguards in."

Although the lido has been refurbished, the pumping station is just as it was in the Thirties. The pool water is recycled through two huge vats, each filled with 20 tonnes of sand, and staff get through 160 litres of chlorine a day.

It is heated naturally to 22C - just right for cooling off after a sunbathe.

Alicen Dines, 37, travelled from Horsham with her sister and their five children, all aged under five. She said: "I'm a huge fan of lidos. I used to live in Clapham and went to the Tooting Bec Lido, which is enormous.

"I think this lido is lovely - it's on a smaller scale but very friendly."

Tanya Seaward, 22, was visiting with baby Hayley as well as her husband and three stepchildren.

She said: "This is the first time I have been here and it's really good for kids. I did think it was a little expensive to get in but I didn't know they sold food. We're coming tomorrow too."

The lido has two sun terraces and many visitors end up staying all day.

Nearby, in Woodingdean, residents are immensely proud of their pool. It opened in 1978 and has served several generations in the community.

Scores of people of all ages were enjoying lying in the sun and messing about in the water.

Caroline Reilly, 45, who serves on the pool committee, said: "It's very popular, especially with people in Woodingdean. But we get quite a few people from Brighton coming and even a few from Saltdean who find the lido a bit cold. This one is heated."

Her friend Elaine Tolhurst, 49, added: "We've been helping here for 15 years and used to swim in the pool before that."

Although not on the scale of Saltdean, its sister pool is still a bit of a suntrap. However, it probably remains more of a hidden gem to most people outside the community.

Pells Pool in Lewes, meanwhile, claims to be the oldest open-air swimming pool in the country and draws people from far and wide.

The facility used to be Olympic-sized but is now just 46m long after new pipes were installed, according to supervisor Chris Chessell.

The pool opened in 1860 and for more than 140 years, people have combined a visit to the facility with a stroll and a picnic along the river.

Chris said: "It's definitely for the general public. We get lots of people from Brighton and Burgess Hill.

"It's mostly families who come down but when it's not good weather, you get the hardened Lewes crew who keep the place open.

"The pool is run by volunteers after the council handed it over because it said there was not enough money. But with the right ideas, this could make a healthy profit - although it's all down to the weather. On a good week, we can bring in £15,000 to £20,000."

Michael Whitehouse had travelled from Brighton with his family. He said: "I used to live in Lewes and came here as a child but haven't been here for many years."

Lewes resident Jane Goldsmith, 56, was visiting Pells Pool with her six-year-old granddaughter Josephine. She said: "My oldest child is 34 and I have been coming here since 1969, although the water has not warmed up in that time!"

Evidence of the growing interest in outdoor swimming pools can be found in Arundel, where a stalwart band of volunteers has finally reopened the town's children's pool.

The Fitzalan Pool opened in 1960 in an idyllic spot overlooked by the town's castle. But its closure in 1999 marked the end of outdoor swimming in West Sussex.

This summer, fund-raisers managed to reopen the paddling pool on the site and they are hopeful of restoring the main pool for next year.

Ruth Kerslake, of the Arundel Pool and Community Sports Centre Appeal, said: "Since we opened, so many people have come to use the pool. One lady came down specifically from London."

Joanna Williams, who runs the Friends of Arundel Pool, said: "We have 150 households joined up. We have raised £30,000 through our own efforts but we also need to get £20,000 a year for running costs."

Appeal director David Wood said a new scheme to enlist company sponsorship was now being launched.

At 10.30am the first groups were arriving.

One of the first in the queue was Judith Watts, 39, who was visiting with six-year-old son Joe.

She said: "I live in Sompting but come to Arundel quite a lot and we noticed an advertising board was out last weekend. We decided to come to check it out.

"Years ago, I used to come when the pool was up and running. When it closed it was such a shame - I suppose it's all down to money.

"I hope they get the money to open the adult pool here in Arundel for next year."