quick fix
If the pipe is accesable then you can do a quick repair. Is the leak at a joint, a fitting (i.e. elbow or a Tee), a tear or is it just a pinhole? In the mean time shut off the water to your hot water heater to stop the leak from spraying. You can use a piece of bicycle inner tube and some hose clamps to cover over the hole and clamp down on the pipe to stop the leak. It may take a couple of tries, but it should work to stop or sigificantly slow the leak. Good Luck
If the pipe is accesable then you can do a quick repair. Is the leak at a joint, a fitting (i.e. elbow or a Tee), a tear or is it just a pinhole? In the mean time shut off the water to your hot water heater to stop the leak from spraying. You can use a piece of bicycle inner tube and some hose clamps to cover over the hole and clamp down on the pipe to stop the leak. It may take a couple of tries, but it should work to stop or sigificantly slow the leak. Good Luck