moisture under house

[David Hickman]

I have a brick house with a crawl space.Under the house the ground is covered with plastic sheeting as a moisture barrier I think.In every low spot in the plastic there is a puddle of water.It appears to be condesating on the topside of the plastic and forming the puddles.I live in a very humid area.Should I get an exhaust fan to pull the moisture out?Would a dehumidifier be more effeciant?Once I get this solved,what do I have to do to prevent this from happening again?