Also, her deed of the water rights in the four parcels provides that all water developed on any of the four lots shall belong to the children in equal undivided shares and shall be put to beneficial use upon those four lots only. The truth of such recital in the deed accepted by appellants is deemed conclusive and no evidence can contradict it. (Subd. 2, Code Civ. Proc., § 1962; Estate of Mills, 137 Cal. 298, 303 [ 70 P. 91, 92 Am.St. Rep. 175]; Knoch v. Haizlip, 163 Cal. 146 [ 124 P. 998].) [6] Appellants contend that the water contract was executed for the specific purpose of enabling defendants to procure a loan on lot 6 and that their rights to the water from lot 2 for use on lot 6 had been established by over 30 years of adverse enjoyment.

This question must be answered in the affirmative. The law is settled in California that it is reversible error for the trial court to fail to make a finding upon a material issue properly raised by the pleadings if, as in the instant case, there is any evidence which would support a finding in favor of such defense ( Due v. Swartz, 22 Cal.App. (2d) 217, 218 [ 70 P.2d 716]; Lyden v. Spohn-Patrick Co., 155 Cal. 177, 182 [ 100 P. 236]; Knoch v. Haizlip, 163 Cal. 146, 153 [ 124 P. 998].) There is no merit in plaintiffs' assertion that defendant is estopped from invoking the defense of the statute of frauds, for the reason that estoppel as to any defense which would otherwise be available to the defendant (appellant) under the facts stated in a complaint may not be relied upon by the plaintiff (respondent) unless the estoppel is pleaded ( Cohen v. Metropolitan Life Ins. Co., 32 Cal.App. (2d) 337, 347 [ 89 P.2d 732].)