Rudy Gestede rescued a point with a late header, which left Sannino lamenting his side's inability to keep out teams in the closing stages of Championship matches this season.
"I'm very disappointed but in English football you have to pay attention to the last, last minute of the game," the Italian told members of the press. "This is the rule of English football.
"We nearly won this game but it was not only this game. Since I joined the club there were many games we have dropped points in the last five minutes of games. This game reflects Watford's season perfectly."
Watford return to action against Sheffield Wednesday on Saturday afternoon.