Question: [![enter image description here](https://i.stack.imgur.com/1gO9Z.jpg)](https://i.stack.imgur.com/1gO9Z.jpg)

Hi there, 

This is some piping to my Saxon hot water system. Just above where the white/green corrosion is is where the leak is.

My question is, can I use plumbers tape on the outside of this to seal the leak? 

I do not want to pull it apart as I don't know what I am doing. I am basically after a quick fix and thought plumbers tape (teflon tape) would suffice. If not are there any other options? (other than the obvious in getting a plumber out (again!).

Answer: 
No. "Teflon tape" is used on the threads of joints, not to seal leaks outside of joints. It's not adhesive like tape, so it wouldn't stick to the outside of the pipe at all.

If you don't know what you're doing, I'd bring in someone who does. Based on the amount of corrosion, it looks like it's been leaking for some time. It could be as simple as tightening the nut, or it might require disassembly and reassembly (possibly with new parts).
You should first turn the water off at the main. ( where the meter is located, usually in the front by the curb) Have a bucket close by to catch what water is left in the pipe. You should be able to turn the bolt just above the corrosion to the left and loosen the connection. Pliers may be needed if it hasn't been loosened in a while. After loosening, it should disconnect enough where you can maneuver the pipe out from under the bolt. Take a look at the pipes condition. If it's threads are still visible and the pipe is still in good shape with the corrosive material mainly where the dripping is on the outside, then u can apply a layer of plumbers tape around the threading and reconnect. The tape otherwise will have no affect on the leak without taking these steps. If the leak continues or the pipe is deteriorating, then disconnecting both ends of the pipe and taking a trip to Home Depot will probably be necessary.