An agreement has now been put in place between the two clubs, with the 25-year-old set to complete a switch to the Madejski Stadium once he has passed a medical.
"We have got a formality to take care of on Monday and I think once that's done and dusted we are hopeful of getting him signed on Monday," Royals boss McDermott told Sky Sports News HD.
"He's a character, a fantastic character. He has done really well for Watford over a period of time.
"For a young man he has played a lot of games, he's got good pace and as a character he will fit in with what we are trying to do here - as has been the case with all of the players I have signed."