In a scrappy and uneventful encounter at Dagenham and Redbridge's Victoria Road ground, Dominic Foley's late free-kick earned a point for the Hornets after Billy Mehmet had put the Hammers ahead on the stroke of half-time.
Following last week's frustrating 0-0 draw with Chelsea at Upton Park, this was another game that should have provided all three points for Hammers, with Foley's strike being Watford's only effort on target all evening.
Injuries and illness forced coach Roger Cross had been forced to reshuffle his line-up and formation for the visit of the FA Cup semi-finalists. The absence of Richard Garcia meant that Christian Dailly moved forward as a makeshift centre-forward, while under-17 Kevin Keen made his third appearance of the season in midfield with David Noble, Don Hutchison and John Moncur all sidelined.
An abundance of central defenders saw Hammers field a 5-3-2 formation, with Gary Breen, Clive Delaney and Elliott Ward making up a central back three, and Anton Ferdinand and Scott Minto filling in as wing-backs.
Despite the change in style and personnel, though, Hammers still dominated for most of the game and it was Dailly who had the early chances, shooting wide after a neat turn on the edge of the area and then blasting over from just six yards out after Daryl McMahon's powerful free-kick had been parried by Watford keeper Richard Lee.
Shaun Byrne then went even closer with a long range effort that struck the crossbar, while Keen saw his cleverly controlled volley drop just inches wide of the post.
It was McMahon and Dailly who combined again to give Hammers a deserved lead moments before the interval, though. The Irish midfielder whipped in a fantastic cross from the left that was headed goalwards by Dailly, but palmed out by Lee as he dived to his left. However, the Scottish international collected the loose ball and turned it back into the six-yard box, where Mehmet was on hand to clip home.
The second half followed largely the same pattern as the first, with neither side enjoying any real spells of possession and, while Hammers found it harder to create the kind of goalscoring opportunities they had enjoyed in the first half, they certainly didn't appear to be in danger of conceding at the other end.
However, with just 12 minutes remaining, Irish defender Delaney gave away a needless foul some 25 yards out and Foley stepped up to curl a superb free-kick past Stephen Bywater - who had been nothing more than a bystander up until then.
Young winger Mitchell Cole came on for his youth team coach Keen straight after to add some pace to the Hammers attack, but Dailly's low left-foot volley that shaved the post with two minutes remaining was the closest they came to snatching a winner.
Watford had the final word when substitute striker Hameur Bouazza was shown the red card in the last minute for a dangerous challenge that left Delaney clutching his face in agony, but it was more of a headache that Hammers were left nursing after yet another seemingly comfortable victory turned into a highly frustrating eighth stalemate of the campaign.
Said Roger Cross afterwards: "For the second week running it was a game we should have definitely won. I wouldn't say we created a glut of chances, but we had enough to have won comfortably and should have had the game sewn up before they scored.
"I can't remember Stephen Bywater having a save to make all game, and it was very disappointing to concede late on because I never thought we looked in danger at the back. Clive gave away a silly foul and it was only ever going to be a set-piece that they scored from.
"I am more frustrated than disappointed with the performance, though. We had to change things around a bit, going to three at the back after playing 4-4-2 all season and the players coped with that as well as they could.
"I thought Christian Dailly was excellent for us at holding the ball up and bringing others into play. He had a couple of decent chances that a regular centre-forward might have tucked away, but that has been the story of our season so far - we haven't had an out and out goalscorer to convert the chances that we create.
"Hopefully Richard Garcia could be that player, but he is injured at the moment, as is David Noble, who has given us that extra bit of quality in midfield recently.
"It's nice to get an unbeaten run going, but we have been the draw specialists this season and I am sure we would be challenging at the top of the table if we could have turned a few of these results into victories."
Hammers: Bywater, A Ferdinand, Breen, Delaney, Ward, Minto,
Byrne, Keen (M Cole 79), McMahon, Dailly, Mehmet. Subs unused:
Tattam, Forde, Pearson, Blewitt.
Watford: Lee, Doyley, Smith, Swonnell, Brown, Dyche (Herd 19),
Fisken, Godfrey (Bouazza 76), Foley, Hand (Young 64), McNamee. Subs
unused: Collins, Watson.