Andreas Weimann gave Watford a 27th-minute lead but Noel Hunt earned his side a point with his 50th minute equaliser.
The point means both the Royals and the Hornets have now failed to register a win in their last six league games and stay in the mid-table region of the npower Championship.
McDermott said: "It's been a frustrating time recently but I think this was a fair result.
"I thought Watford came with a good energy about them and played some good stuff in the first half when we weren't at our game.
"We didn't do well in the final third and that makes such a difference. We had numerous crossing opportunities but didn't make the most of those."
Source: PA
Source: PA