Is the Prophet's urine pure, and is it true that one of the female Companions drank it?

There are two narrations concerning the drinking of the Prophet's (peace be upon him) urine: one from Umm Ayman and the other from Barakah, Umm Yusuf. Both are weak due to defects in their chains of transmission. The default is that the Prophet's (peace be upon him) urine is like that of other humans, and there is no authentic text proving its purity. He (peace be upon him) used to cleanse himself after relieving himself.