My basement drain has a trickle feed from the back of the laundry sink, each time a tap is used water flows to drain. Using a carpet cleaner from tap caused a back pressure which leaked at back of sink. My question is: Is this trickle necessary and is it deliberately fitted loosely to create a ventura effect when in use?
Thanks in anticipation
Alan

This is called a trap primer and is used so that the trap seal does not evaporate. If the floor drain's used the primer's unnecessary. If not used too often you can still disconnect the primer and fill the floor drains trap with motor oil that will not evaporate. Good luck. Tom