Praise be to Allaah.
A Muslim may do wudoo’ in whatever way is easy and practical for him, whether sitting or standing. He may also drink standing or sitting, although it is better to drink sitting down. He may also urinate standing up if necessary, as long as no one can see his ‘awrah (private parts which should remain covered) and there is no danger of the urine coming back on him. It is better to urinate sitting down, because this is how the Prophet (peace and blessings of Allaah be upon him) did it in most cases.