How can a Muslim perform prayer at their workplace in the United States if they cannot use water for Istinja' after relieving themselves, and thus remain impure during work hours?

If a Muslim relieves himself, wiping the two excretory organs with cleansing tissues is sufficient to achieve purity, and using water is not obligatory, though it is preferable. So, if he removes the traces of impurity with tissues, he can leave the bathroom, perform ablution, and pray. He should not delay the prayer beyond its time, and he does not need to perform a ritual bath upon returning home.