Responsa על עירובין 175:16

On the Sabbath, a Jew is not permitted to pour sewage into a stone-trough, which is situated partly in his yard and partly in the public domain (used to carry off sewage into the street), unless the trough is covered for four cubits length in the public domain.
SOURCES: Cr. 69; Pr. 31; L. 341; Rashba I, 850; Mord. Shabb. 375.