I noticed the drain cover on the path outside my house had come off the other day and moved about 10cm away like it floated there. The water seems really high and it seems to be damp around it like the water is coming up and leaking over (probably why the cover had come off and maybe floated away). It hasn't been raining at all the past few days and has been very dry so it's not a sudden amount of rain or anything. I am wondering if this is related to a bathroom issue I have also. The bathroom window is right inside where this drain is. The sink sometimes drains very slowly if you run a lot of water in it or the shower is on. I tried cleaning with a 1.8m snake and also with liquid and crystal drain cleaner and the snake came up with nothing.. It's only when you run a LOT of water down it or the shower is on that it will then drain slowly but it does drain. Normal use the sink empties straight away. Does anyone know what this drain is for and what might be causing the problem? Is there a solution and is it related to the bathroom issue? Also how can I stop the drain floating away like that because I'm worried someone will not see it and land in the hole.