Rickmansworth School's pool re-opened this week following a refurbishment, which cost more than £500,000.
The swimming facilities at the Scots Hill secondary school have been completely renovated since the dilapidated pool closed in 2012.
A grant of £380,000 from the Education Funding Agency and a further cash boost of £150,000 from Sport England financed the redevelopment.
Simon White, director of PE at Rickmansworth School, said: "It’s a fantastic facility and we’ve developed it so that lots of the local schools can use it.
"We are the hub school of the School Sports Partnership and we’re eager for neighbouring schools to use it and get their children up to the standard 25 metres.
"It’s not just our school that will use the facilities, but the local community."
It is anticipated that the 25 by 7.5-metre pool will be used by more than 450 students on a weekly basis
The changing facilities also underwent a complete transformation, with unisex changing areas, individual shower cubicles and a separate group change room being installed.
Since the pool closed in 2012, swimming was removed from the curriculum.
However, the reinstatement of the sport on the sport syllabus will mean not only will pupils be able to practise a valuable lifeskill, but will also have the opportunity to train competitively.
Mr White said: "We’re hoping to improve the standard of our swimming and establish it at a high level.
"We’re looking to enter the district and hopefully national leagues and our aim is for all of our children to be able to swim at least 25 metres. For me, it’s one of the most important life skills that they learn at school."
Ben Hawkins, site and lettings manager, said the school took a "difficult" but necessary decision when the pool closed in 2012.
The old pool
Mr Hawkins said: "We had to do it. The building was built in 1972 and designed for ten years. It was designed for a certain amount of people using that pool at any one time and the amount of students has doubled, even tripled, in the last 50 years."
The school opened its new sports hall and astroturf pitch last year.
Mr Hawkins added: "The new sports facilities we have here will hopefully mirror the refurbished pool, so that people who are using that facility can use the pool as well. I truly believe that we have got the best facilities in the district."
The pool’s official opening ceremony took place on Tuesday, with Junior World Champion, Caleb Hughes, attending the event.
Keith Douglas, headteacher, said: "School swimming pools have been lost all over the country because of a lack of investment. By working with the help and assistance of Three Rivers District Council, we have a pool which not only serves the pupils of Rickmansworth School, but also the local community."
He added: "I would like to thank everyone involved in securing this vital asset for the pupils of Rickmansworth School, local primary children and the residents of Croxley Green."
The pool is available to community groups from 5pm to 10pm on Mondays to Fridays and from 8am to 6pm on Saturdays and Sundays.
It is also open for hire during school holidays.
Watford Swimming Club and Active Swim will be the main users during the community use period.