The Prophet (peace and blessings be upon him) said:
"Indeed, water does not become affected by janabah (that is, it does not become impure through use by a person in a state of major ritual impurity)."
Hadith Referenceصحیح الجامع الصغیر / حرف الألف / 1927
Hadith Gradingالألبانی:صحيح
Hadith Takhrij[د ت هـ حب ك هق] عن ابن عباس. المشكاة ٤٥٧، صحيح أبي داود ٦١.