An archaeological team is investigating the cause of flooding at Hailes Abbey in the Cotswolds.
The abbey was a victim of the Tudor dissolution programme
The medieval building is normally flooded every six or seven years.
English Heritage is concerned that the damp conditions could affect the remaining masonry of the 750-year-old Cistercian monastery.
Niall Morrissey, of English Heritage, said: "The periodic flooding has meant that the site can be up to 30cms underwater which cannot be good."
He added: "16th Century records show us that the site flooded regularly 500 years ago but we are determined to find out the cause.
"The archaeological investigation we are carrying out will help us decide what we can do without disturbing valuable archaeological remains."
There will be a viewing platform available for the public to watch the archaeological team at work.
Cistercian monks lived and worshipped at the site until its dissolution under Henry VIII on Christmas Eve 1539.