Before you start to solder,you must ensure that water is drained completely.
Turn off the water at the major valve in your house as well as open up nearby taps to entirely drain pipes the pipe with the dripping joint. Dry the exterior of the arm joint and also sand (120-grit paper or cloth) around the leaking joint to remove all surface area rust. Apply soldering flux around the entire joint and use heat with a lantern until the old solder thaws. Include new solder until a shiny ring of solder reveals all over the joint. Let the pipeline cool for five minutes, then transform the water back on and cross your fingers that you quit the leak.
You will need the following tools :
Slip joint pliers
Other things required :