The water knot has many uses for the angler. It can be used to link hooklength to mainline, it can be used to join a paternoster link to a mainline, and it can even be used to join mono to braid.
Many anglers use this knot to link their pole mainline to the hooklength, especially when fishing delicate rigs, because it is far more direct than the more commonly used loop to loop technique.
Lay the two lines you wish to tie alongside each other.
Form a substantial loop using the two lines
Ensure the two lengths of line are together and thread the pair of tags ends through the loop three times.
Moisten the knot with saliva or water and slowly pull it tight. Trim off the tag ends accordingly to either create a straight profile when joining a mainline to hooklength, or cut the tag ends to create a paternoster link for legering purposes.