How Can I Find Free Public Property Records On The Internet?

If I had the exact address of a house built on a piece of property, that was at one time farm land, how or where on the internet could I find public records of what was on that land, before the house was built? The house and the houses around it were infiltrated with excessive amounts of mold. I need to find out if the houses were built on some kind of toxic waste land, or if there were springs underground, or if something has been covered up. The house is located in the Little Britain Township, in Lancaster, PA. Thanks. Also, any college professors or students that know of any kind of toxic chemical that could possibly grow mold, I’d be interested in hearing about it. I once read that Erin Brockovich found excessive amounts of mold in her house in Conejo Valley, CA. and was wondering if any kind of toxic chemical being dumped on land could cause it. If it helps a mold test was taken, and Penicillium,Asperguillius, and Cladisporin were found. No water leaks were ever found in the house