Should I pray while urine is still flowing, or should I wait 30 minutes for it to stop flowing, even if the prayer time expires?

If the worshiper fears that the time will expire before his impurity ceases, he should perform ablution (wudu) and pray according to his condition, taking precautions by tying a cloth over the affected area to prevent the spread of impurity. He is not obliged to delay relieving himself if he is in need; rather, he should relieve himself, then perform ablution and pray. If he can relieve himself before the prayer time begins, in such a way that the discharge ceases, he should do so. If urination continues for hours without stopping, then he has سلس ( سلس البول - urinary incontinence), and the ruling for such a person is the same as for someone with continuous impurity; he performs ablution after the time for each prayer begins, and whatever exits from him after ablution within the prayer time does not harm him, even if it touches his clothes or body, after he has done what he can to take precautions and ensure cleanliness.