Pat Sajak has caused more than $100,000 of misfortune to his neighbor who is now suing him for gross sprinkler malfeasance ... this according to a new lawsuit.
Jacob Saleh claims in the suit -- obtained by TMZ -- Pat's sprinkler system was a disaster ... broken sprinkler heads, broken pipes, defective timers and other problems with the irrigation system.
Saleh says the "Wheel of Fortune" star did nothing to fix the problem on his $3 million estate ... and as a result there was massive flooding on Saleh's property ... causing the soil to significantly shift.
Saleh says his retaining walls were damaged, and there was large cracking and shifting of the pool. He's also worried his foundation might be damaged.
According to the lawsuit ... Saleh confronted Sajak ... to no avail. In fact, he says Sajak admitted he had broken pipes and defective sprinklers but did nothing to fix any of the problems.
According to the suit ... the repair costs are estimated at $125,000.
We called Pat's rep for comment ... so far no word back.