Responsa על בבא בתרא 11:5

Q. The community pronounced the ban against anyone who would buy the house of a certain Gentile. Is one permitted to exchange houses with that Gentile? Signed: R. Menahem.
A. Exchange is equivalent to buying, and is included in the above ban.
SOURCES: Mord. B. M. 395; Agudah B. M. 170.

Q. Some of the water from A's roofs used to drain into the Synagogue courtyard. Subsequently, A opened a spout, for the purpose of draining the water off his roof, which spout extended into the synagogue courtyard and thus all the water from A's roof was poured into the courtyard. The members of the community objected to this.
A. A must remove his spout.
SOURCES: Pr. 236.