Our neighbor is claiming that the water that he has in his cellar is water from my property and sprinklers system. I have told him we all have sump pumps placed in our cellars in the neighborhod for when it rains water soaks the ground and seeps through. The walls around these cellars are not waterprofed. These cellars are used to place the heating equipment and water heater. I tried explain to him that that is how they buid and how they took care of any water seepage.I did tell him that the pump must pump the water away from the building and not just out of it. I have told him that sprinlkers system water will not go down 10-12 feet deep and cross over horizontially 15 feet. His cellar has windows above, a well that is not covered and when it rains water seeps back. Also when his pumps shoots out the water unto the adjacent driveway which is all craked and open the water just returns.
Sprinkel some egg dye color in the cracks and if water comes back it will be colored, also like Plumbhill says extend his pipe out so it don come back. You could put dye down and run water hose and see if it does come back.