Hi all, bit of a drainage issue perhaps.
The downstairs toilet has started draining slow. If you flush in succession 2-3 times it fills up, and makes a strange noise as it drains away (very slowly) like a humming noise (not a macerator).
There is a manhole at the front of the property. When flushing the ensuite at the front of the house the water runs through (soil stack by front door).
Flushing the downstairs loo on side of house (not sure of stack location), or the upstairs loo at the back of the house ( and another soil stack) and nothing comes through.
Would all the drains flow into that one manhole, or is it likely there is another one somewhere, possibly under gravel or the rear decking.
It's a Detached house at end of row. Drainage plans for the property searches only show the main drains by the road, not the house ones
Any ideas welcome before I call in the professionals!