Victory at Vicarage Road pushed Jurgen Klopp’s side three points clear of Manchester City, a further point ahead of Manchester United and nine clear of Arsenal in sixth.
A third defeat in four games means Watford, on 40 points, are still not mathematically assured of safety though it would take a remarkable turn of events for them to be dragged into the mix.
However a drab display by the home side will have done little to ease the pressure on Walter Mazzarri, though the Hornets manager has been insistent over recent weeks that he will be at Vicarage Road next season.
Liverpool were little better and were not aided by the loss of Philippe Coutinho to injury after only 13 minutes but benefitted from the game’s one moment of unquestionable quality as a spectacular Emre Can bicycle kick gave them the lead in first-half added time.
There was little improvement in quality during the second half, where substitute Adam Lallana spurned a chance for Liverpool on the break.
A Daryl Janmaat cross nearly caught out Simon Mignolet in the closing minutes as Watford upped the pressure in the closing moments, but to no avail, with a Sebastian Prodl volley cannoning off the crossbar in the final seconds of added time.