Zaid Alsalami, Shaykh Dr Zaid Alsalami is an Iraqi born scholar, raised in Australia. He obtained a BA from Al-Mustafa University, Qom, and an MA from the Islamic College in London. He also obtained a PhD from... Answered 1 month ago

Bismihi ta'ala

As Muslims, we do istinja`, or wash ourselves after using the toilet, not only because it is more hygienic and cleaner, but also to stay in the state of taharah, especially for salat. 

This is necessary, wherever you may be, even in public office, if you are there regularly. You can use a water bottle, and it does not need to be excessive amount of water as well. 

If you do not wash yourself, then no, you cannot pray in such a state, especially if it is after urinating. Your option is to either wait until you go back home, wash yourself, and then pray, or do as recommended above, and pray on time. 

And Allah knows best.