Water runoff and sludge from landfills is treated, however only final very time consuming steps of biological sedimentation and treatment can remove most of them. Or very fine reverse osmosis or treatment with micron level filters, very energy intensive. So they do tend to end up in clean drinking water.
There are many sources and no norms.
Sometimes even metals bordering on norms can be detected near landfills.
I had a link with site in Sweden barely keeping norms for lead and cobalt... due to organic decomposition and incomplete runoff collection. Bad enough that I wouldn't build a well within some 10 km radius.
Read up on what happens to all this thing called leachate.
This is a main reason why European Commission wants the landfills to remain as exception.
Sometimes even metals bordering on norms can be detected near landfills.
Sample efficiency ranges: https://www.sciencedirect.com/science/article/abs/pii/S00431...
I had a link with site in Sweden barely keeping norms for lead and cobalt... due to organic decomposition and incomplete runoff collection. Bad enough that I wouldn't build a well within some 10 km radius.
Read up on what happens to all this thing called leachate.
This is a main reason why European Commission wants the landfills to remain as exception.