New legislation comes into force on May 9.
Farmers and landowners must ensure they use greater due diligence to avoid falling foul of new laws on illegally stored waste.
Failing to comply could cost tens of thousands of pounds, and leave the farmer with a criminal record, according to Angus Evers, partner at law firm Shoosmiths.
Previously, regulators only had powers to force the removal of any waste which had been illegally dumped.
But new legislation, which comes into force on May 9, means the Environment Agency, Natural Resources Wales and local authorities would be able to serve notice requiring occupiers to remove illegally stored waste, even if it was brought to the land legally.
It will be a criminal offence to fail to comply with such a notice.
If the land was unoccupied, or the regulator could not identify the occupier without incurring unreasonable expense, the notice could be served on the landowner.
And if the occupier failed to comply with the notice, or successfully appealed against a notice, the regulator could serve a new notice on the owner of the land.
Mr Evers said it was often difficult to prove waste was not being stored illegally on a site where it had been deposited lawfully, especially if the occupier’s permit had expired, been revoked or the occupier had changed.
“This is crucial, despite Government’s reassurances safeguards will be in place to protect those farmers and landowners who have become involved unknowingly,” said Mr Evers.
Farmers and landowners may find themselves liable for the costs of removing waste brought to their land lawfully but stored illegally.
“It is essential greater due diligence is undertaken when considering potential tenants and other occupiers of land who intend to use it for waste management activities,” he added.
If occupiers were already in place, he advised landowners to review any environmental permits or exemptions held to ensure the site was operating lawfully.
Mr Evers said landowners should consider requiring occupiers undertaking waste management activities to provide a deposit or other security which could be used should they incur any liabilities.
Flytipping and illegal waste deposit sites have grown as people try to avoid landfill taxes.
Changes were applied to the taxes on permitted and non-permitted landfill sites on April 1, but the tax rates were different in England and Wales.