October 30,1954, the Washington Building Company leased “that certain store space known as 1025 Pacific Avenue,” in Tacoma, Washington, to Donald H. Hutch-ins for an ice cream and soda fountain business. November 30, 1955, the lease was assigned to Arthur A. Riebli and George Hoertrich, Jr., with the consent of the building company. During the weekend prior to October 29, 1956, *819a water pipe imbedded in the cementlike floor of the leased premises ruptured. Monday morning at 7:30 a. m., the maintenance superintendent of the building company discovered that the basement of the building had been flooded. The flow of water from the ruptured pipe was shut off by a valve which controlled the service of water to the leased premises. The water caused damage to some doors stored by the building company in a basement storeroom, to merchandise stored by the Washington Camera Mart in its basement storeroom, and to a rug on the floor in the basement safe-deposit vault lobby of the United Mutual Savings Bank.
The Washington Camera Mart brought suit against Riebli and Hoertrich to recover for its loss. The bank sued Riebli, Hoertrich, and the building company. The building company cross-complained against Riebli and Hoertrich for damages to its doors and for indemnity for any damages it might be required to pay to the bank. The causes were consolidated for trial.
The court entered judgment for both plaintiffs and also entered judgment for the building company on its cross-complaint. Riebli and Hoertrich have appealed.
The evidence disclosed, inter alia, (1) that the respondents’ premises were damaged by water; (2) that the water came from a ruptured pipe imbedded in the cementlike floor of the premises leased by the appellants; (3) that the pipe was installed in 1947, with the consent of the building company, by a former tenant when he remodeled the premises, and had since remained untouched; (4) that water was supplied by the building company to the appellants’ premises through a system of pipes which it maintained and over which it retained control, the water being piped to a reservoir on the top floor of the building and from there to the various parts of the building; (5) that the appellants were not assignees of Fox, who had installed the pipe, but were in possession as the assignees of the Hutchins lease, and (6) that the lease provided that the tenants had the duty to keep the leased premises in repair and, under cer*820tain conditions, to save the building company harmless from occupational liability.
The court predicated appellants’ liability to the Washington Camera Mart and to the bank upon the doctrine of res ipsa loquitur. The court erred in applying the doctrine to the facts of this case.
Before the doctrine of res ipsa loquitur can be applied, exclusive control of the offending instrumentality by the appellants must be established by the evidence. In this regard, Prosser on Torts (2d ed.) 204, § 42, states the rule as follows:
“It is never enough for the plaintiff to prove merely that he has been injured by the negligence of someone unidentified. Even though there is beyond all possible doubt negligence in the air, it is still necessary to bring it home to the defendant. On this too the plaintiff has the burden of proof by a preponderance of the evidence; and in any case where it is clear that it is at least equally probable that the negligence was that of another, the court must instruct the jury that the plaintiff has not proved his case. . . .
“This element usually is stated as meaning that the defendant must be in ‘exclusive control’ of the instrumentality which has caused the accident. . . .
“. . . It would be far better, and much confusion would be avoided, if the idea of ‘control’ were discarded altogether, and we were to say merely that the apparent cause of the accident must be such that the defendant would be responsible for any negligence connected with it.”
In Morner v. Union Pac. R. Co., 31 Wn. (2d) 282, 294, 196 P. (2d) 744 (1948), this court said:
“ . . . one of the elements essential to the invocation of that doctrine [res ipsa loquitur] is that the party charged with actionable negligence must have sole and exclusive control of the agency or instrumentality which actually caused the injury. If there is no such exclusive control, or if the injury was caused, or may reasonably be said to have been caused, by the concurrent acts of two or more persons or agencies functioning independently of each other, the doctrine does not apply.”
Accord, 1 Shearman and Redfield, Negligence (Rev. ed.) 153, § 56; 65 C. J. S. 1014 et seq., § 220 (8).
*821In Hogland v. Klein, 49 Wn. (2d) 216, 298 P. (2d) 1099 (1956), we recognized that the requirement of control does not mean actual physical control, but refers to legal control or responsibility for the proper and efficient functioning of the instrumentality that caused the injury.
Under the facts of this case, was the offending pipe under the exclusive control of the appellants?
Respondents rely upon Kind v. Seattle, 50 Wn. (2d) 485, 312 P. (2d) 811 (1957). In the cited case, a water main was held to be under the “exclusive control” of the city, when it was installed by the city, maintained by the city up to and at the time of the accident, and the water was supplied by the city. See, also, Klise v. Seattle, 52 Wn. (2d) 412, 325 P. (2d) 888 (1958).
In the instant case, the appellants did not install the offending pipe. They did not select the kind or quality of pipe used. They had no control over the water supply. The evidence failed to establish the element of “exclusive control,” which is a prerequisite to the application of the doctrine of res ipsa loquitur.
Further, the doctrine of res ipsa loquitur is based in part upon the theory that negligence will be presumed because the defendant either knew of the cause of the accident, or had the best opportunity of ascertaining the cause and, therefore, should be required to produce evidence in explanation. Shay v. Parkhurst, 38 Wn. (2d) 341, 229 P. (2d) 510 (1951); Morner v. Union Pac. R. Co., supra; Lynch v. Ninemire Packing Co., 63 Wash. 423, 115 Pac. 838 (1911).
In this case, there was no proof that the appellants had prior knowledge of the cause of the accident or that they had the best opportunity to know of it. When they took possession of the premises, the imbedded pipe was in place and had remained there untouched during their occupancy.
There remains the question of whether the judgment in favor of the Washington Building Company and against the appellants can be sustained because of the following provisions of the lease:
*822“The Parties Hereto Further Agree, As Follows: . . .
“(2) Throughout the term of this lease, the Lessee will take good care of the demised premises and appurtenances, alterations and improvements, and will keep same in good repair, and at or before the end of the term will repair all injury done by the installation or removal of equipment and fixtures, it being understood that the Lessee shall have the right to remove equipment and fixtures; and, at the end of the term, the Lessee will quit and surrender the demised premises, with all alterations and improvements, in good order and condition, reasonable wear and damage by the elements excepted. . . .
“(6) The Lessor shall not be liable for damage caused the Lessee by bursting or leaking of any water, gas, or steam pipe by accident or by neglect of other tenants or occupants of the building or their employees. . . .
“ (8) The Lessor shall have the right to enter the premises at reasonable times and intervals to examine the same or to make repairs or alterations. . . .
“(11) The Lessee agrees to use the leased premises as a careful and prudent person would use his own, and upon the expiration of the term to surrender the premises to the Lessor in as good condition as at the beginning of the term of this lease, save for wear and tear from reasonable and careful use. . . .
“ (14) The Lessee shall keep, save and hold harmless the Lessor from any and all damages and liability for anything and everything whatsoever arising from, or out of the occupancy by, or under, the Lessee, the Lessee’s agents or servants, and from any loss or damage arising from any fault or negligence by the Lessee, or any failure on the Lessee’s part to comply with any of the covenants, terms and conditions herein contained, or otherwise, or whether it be caused by, or be due to, the failure of the Lessee to perform any of the covenants herein, expressed or implied, that are to be performed by the Lessee.”
Respondents rely upon § 14, supra. Liability under that section of the lease arises upon (1) appellants’ failure to comply with the terms of the lease, and (2) damages arising from or out of appellants’ occupancy of the premises.
As to (1), it was not shown that appellants failed to comply with the terms of the lease. Regarding (2), we are of the opinion that, construing the contract as a whole, the parties intended that the appellants were obligated to *823“take good care” of the leased premises during their occupancy, and to make a reasonable and careful use thereof. They were liable only for damage caused by unreasonable and careless use of the premises. The imbedded pipe in some manner ruptured during the appellants’ occupancy. The fact of the rupture alone does not establish that the use of the premises by the appellants was unreasonable or careless. The burden of proving that the water damage was caused by appellants’ failure to comply with the terms and covenants of the lease, or by their unreasonable use of the premises, was not met by the respondents.
Nor does the covenant (§2, supra) which placed upon the appellants the duty to repair make them insurers of latent defects in the premises. The covenant to repair carries with it no more than the duty to repair known defects or defects which could have been discovered by the exercise of due care. Martindale Clothing Co. v. Spokane & Eastern Trust Co., 79 Wash. 643, 140 Pac. 909 (1914); Bernhard v. Reeves, 6 Wash. 424, 33 Pac. 873 (1893).
There is no evidence in the record before us that the defect was known to the appellants or that appellants, by the exercise of due care, could have discovered it. The proof established nothing more than a latent defect for which appellants assumed no contractual liability.
Finally, respondents contend that the offending pipe was a trade fixture. Assuming, arguendo, that the pipe, at the time it was installed by the then tenant, Fox, was a trade fixture and so regarded by Fox and the owner of the building, it lost its identity as a trade fixture and became part of the building when it was leased by the owner as a part of the over-all premises to the appellants’ assignor, Hutchins.
“ ‘The true criterion of a fixture is the united application of these requisites: (1) Actual annexation to the realty, or something appurtenant thereto; (2) application to the use or purpose to which that part of the realty with which it is connected is appropriated; and (3) the intention of the party making the annexation to make a permanent accession to the freehold.’ ” Forman v. Columbia Theater Co., *82420 Wn. (2d) 685, 695, 148 P. (2d) 951 (1944), quoting with approval from Filley v. Christopher, 39 Wash. 22, 80 Pac. 834 (1905).
Applying these tests to the facts in the instant case, the pipe was securely imbedded in the concretelike floor, and was applied to the use of these premises as an ice cream parlor and soda fountain. The actual intention of Fox, who made the annexation, does not appear, but, from the above and from the fact that he did not remove it at the termination of his lease, we must presume that his intention was to make the pipe a permanent annexation to the freehold. Under these facts, it is clear that the pipe became a permanent part of the building company’s water supply system and was leased as a part of the freehold to appellants’ assignor.
For the reasons stated, the judgments are reversed, and the causes remanded with instructions to enter judgments dismissing the complaints and the cross-complaint.
Weaver, C. J., Hill, Donworth, Finley, and Foster, JJ., concur.