Environment Agency data seen and analysed by ENDS shows the locations of 1,287 of old landfill sites containing hazardous waste, which would pose a risk to human and health and the environment if it were to escape. The data also shows the locations of a further 413 sites whose contents remain unknown to the agency, due to their age and lack of documentation.
If you are aware of any old landfills not shown on the map, please get in touch with ENDS - rachel.salvidge@haymarket.com - and help us create a more comprehensive picture.
Click here to read ENDS' toxic landfill investigation in full.
Some of the landfills may have been removed where development has taken place, but the majority remain in place.
Click here to read more about how toxic landfill sites can harm the environment.
MAPPED: England's healthiest and most polluted rivers
Scroll down for a map with additional detail.
Any errors in the locations of the landfills sites are errors originating in the Environment Agency dataset