I am getting a sewer smell from the floor drain in the basement. There is a backdraft from the drain. I can feel a not so pleasant breeze. I have tried pouring water down the other floor drains and this particular drain is used every day. I tried pouring a few pails of water down the vent on the roof to see if it was plugged and it wasn't. What's next?

Jacksonon

If a floor drain is not holding water it is likely that it either is leaking out or a trap is not installed or it is not properly vented and when you use large amounts of water the trap on the floor drain is sucked out.