Responsa על בבא בתרא 34:1

Q. B constructed a stone duct near A's wooden house. A objected and B made a written promise to compensate him for any damage the duct might cause to his house. A now demands that B remove his duct because it occasionally permits water and sewage to flow into his house, and he objects to being forced to sue for damages every time it occurs. B claims that water flows into A's house only when the duct breaks. He promises to keep the duct in good condition, but refuses to remove it.
A. B must remove his duct from A's wall for a distance of 3 tefahim (hand-breadths). If the water should, nevertheless, continue to flow into A's house, it is for A to protect his wall by whatever means he sees fit, but he can demand nothing of B.
SOURCES: Cr. 3, 4; Pr. 92; L. 357; Mord. B. B. 520.