Fiqh-us-Sunnah Volume 1, Purification and Prayer, Fiqh 1.019.
Section : One should not urinate in bathing places or in still or running water.
‘Abdullah ibn Mughaffal narrated that the Prophet said, “None of you should urinate in a bathing place and then make ablution in the water. The majority of waswas comes from that.” This is related by “the five,” but the statement, “and then make ablution in it” was only related by Ahmad and Abu Dawud. Jabir said the Prophet forbade urinating in still as well as running water. (Related by Ahmad, an-Nasa’i and Ibn Majah.) In Majma az-Zuwaid it states, “This was related by at-Tabarani, and its narrators are trustworthy.”
If there is a drain in the bathing place, it is permissible to urinate into it.