Video from @LeeSimmo73 on Twitter.
Flooding has blocked the road outside Sheffield Children's Hospital, closing the pick up and drop off points.
South Yorkshire Police officers discovered the burst water pipe on Clarkson Street early on Friday morning.
The force is asking people to avoid the area unless they have hospital appointments.
The main entrance to the hospital can still be accessed on foot.
Sheffield Hospital said in a statement: "We are aware of the road closure due to a burst water pipe outside of the hospital.
Services are continuing to run as normal. However, our pick up and drop off area outside the main entrance to the hospital is closed.
"You can still reach the hospital as a pedestrian. If you need to be dropped off directly to the hospital, you can briefly drop off or pick up at our Emergency Department entrance.
"We advise patients and families coming to the hospital today to allow more time for travel and parking in order to attend their appointments at their allocated time. Our clinical teams are aware of the situation and aim to see patients even if they’re delayed."