Williams, J.

In this action of tort there was evidence that the plaintiff owned a house on Tuttle Street in Dorchester which was connected with the street sanitary sewer by a soil pipe. Sometime in December, 1946, the sewage from the house “became sluggish” and about the middle of January, 1947, “backed up into . . . [the plaintiff’s] kitchen sink . . . set tubs and cellar, causing damage.” Investigation showed that there were two jagged breaks in the soil pipe at or near its junction with the sanitary sewer, and that sewage from the plaintiff’s house was draining into the ground. Early in 1946, the defendant had installed a storm sewer in Tuttle Street under a contract with the city of Boston. The work was completed on March 23. In the process of constructing this sewer a trench three feet wide and six feet deep was excavated by means of a steam shovel. The storm sewer when installed was about a foot or a foot and a half away from the sanitary sewer and parallel to it. The soil pipe passed under the storm sewer to the sanitary sewer and was about ten inches to one foot “deeper in the ground than the storm sewer.” A photograph, which was introduced in evidence, showed “the break in the soil pipe where it connected with the sanitary sewer.”

The defendant testified that “he made no investigation to determine where the soil pipe leading from the plaintiff’s house was,” and that he found no evidence of sewage or seepage in the trench when he opened it or when he filled it in.

The plaintiff has excepted to the entering of a verdict for the defendant under leave reserved. The record discloses no evidence as to the material of which the soil pipe was made, the length of time the pipe had been in the ground, the nature of the soil in which it was laid, and the means by which it was connected with the sanitary sewer. While an *198 expert witness called by the plaintiff testified that “sewage from the plaintiff’s house was draining into the ground and that it had acted like a dry well until it had reached the saturation point,” he expressed no opinion as to the length of time the sewage had been escaping. The plaintiff relies on the rule res ipso loquitur. This rule “merely permits the tribunal of fact, if it sees fit, in the absence of a finding of the specific cause of the occurrence ... to infer from the occurrence itself that it would not have happened unless in some respect the defendant had been negligent . . . the .tribunal of fact must be able to find, either by expert evidence ... or by its own common knowledge . . . that the mere occurrence of the accident shows negligence as a cause.” Roscigno v. Colonial Beacon Oil Co. 294 Mass. 234, 235. We have here no expert opinion as to the cause of the breaks, and the common or ordinary knowledge possessed by a jury would not warrant them in finding that it was more probable that the breaks in the plaintiff’s pipe occurred because of some'act of the defendant rather than from some cause for which he was not responsible. A verdict in favor of the plaintiff necessarily would be based on speculation' and conjecture. See Craig v. Leominster, 200 Mass. 101; Bigwood v. Boston & Northern Street Railway, 209 Mass. 345, 349; Andrew Dutton Co. v. Boston, 234 Mass. 54; Moore v. Amesbury, 268 Mass. 462, 466, and cases cited; Brownhill v. Kivlin, 317 Mass. 168, 170. Compare Sargent v. Massachusetts Accident Co. 307 Mass. 246; Black v. Boston Consolidated Gas Co. 325 Mass. 505, 508.

Exceptions overruled.