Hi there -

I have a smell that is in my 2nd floor washroom every spring. It smells the strongest underneath the bathroom sink. The smell starts in April (after ground starts to thaw and usually disappears in June or July.
It smells very earthy, almost like wet dirt.
On really smelly days (the warmest days in spring) we can smell this on main floor and basement of house directly under the 2nd floor washroom.
We had a plumber in today and he suggested that this could be from 'ground water' but offered no solutions.
Please help. I have a toddler and expecting another child, I worry about possible health impact of this.
Thank you.