Jon and Kate Gosselin are finally free to start tappin' again -- because someone finally paid their outstanding water bill.



As TMZ previously reported, a tax lien was filed against the Gosselins after Lancaster County claimed they owed $2,691.75 in city water charges.

But according to new court documents filed last week, the Gosselins are finally in the clear -- because someone finally forked over the cash.

One problem down -- about 30 billion to go.