The Hornets fell behind to Lewis Dobbin’s opener in a scrappy first 45 minutes but the game really came to life when Othmane Maamma equalised 10 minutes after the break.
Substitute Kwadwo Baah was highly influential as his side went in front two minutes later, an own goal sending the away support wild as they prepared to celebrate a first away win of the calendar year.
Milutin Osmajic drew his side level, though, before Formose Mendy struck the inside of the post with a left-footed volley from distance.
Edoardo Bove was thrown on for his debut in the final stages as Watford looked the more likely but, in the end, Still had to settle for a point.
Stephen Mfuni battles (Image: Alex Cozzi/Watford FC)
In a system that seemed to alternate between a back three and a back four, Watford dominated the ball in the early stages – though it was Preston who had the first opening.
Papy Mendy gave possession away and Alfie Devine was slipped in on goal, but Saba Goglichidze was quickly across on his first Hornets start to block.
Sustaining quality periods of football was difficult on a very bobbly surface, Maamma having Watford’s first serious effort when he cut in off the left but his effort deflecting into Dai Cornell’s arms.
Just shy of the 20-minute mark, the hosts took the lead.
Ben Whiteman drove into space down the left and crossed low, Dobbin opening his body up and side-footing beyond Egil Selvik.
The game remained scrappy but Watford tried to work their way back into it, Luca Kjerrumgaard’s looping header from a Maamma cross tipped away by Cornell.
Luca Kjerrumgaard in the action (Image: Alex Cozzi/Watford FC)
Preston were dealing with the conditions better, though, Dobbin seeing an effort deflected over after Odel Offiah crunched into Giorgi Chakvetadze.
Down the other end, Imran Louza powered straight at Cornell from the edge of the box but the Hornets went in behind.
Baah replaced Chakvetadze down the right at the break as Watford sought a way back into the game.
They struggled in the opening minutes of the half but dramatically turned things around soon afterwards.
Louza kicked it off, producing a lovely touch and then finding Maamma to cut inside and roll home the leveller.
Two minutes later, remarkably, they were ahead. Baah burst onto a Mendy pass and crossed into a bundle of bodies, with a Preston defender appearing to turn the ball into the net.
Watford settled from there, substitute Formose Mendy seeing a header blocked – but just as they had the upper hand, it was their hosts who scored from nowhere.
Othmane Maamma and Kwadwo Baah celebrate (Image: Alan Cozzi/Watford FC)
Mendy and Mattie Pollock tried in vain to halt a counter-attack but it was fed to Osmajic to make it 2-2 with a sweet finish.
Watford kept at it, though, and continued to threaten.
Pollock had his own header blocked before Mendy struck a left-footed volley from distance that hit the inside of the post, rolled along the goal-line and out. So unlucky.
Still’s side looked the likelier and with five minutes remaining, Baah swung a left-footed effort agonisingly wide.
Bove made his debut off the bench as Watford continued to seek a winner, though Jordan Storey headed over unmarked at the other end in added time.
Watford: Selvik; Abankwah, Pollock (Petris 78), Goglichidze (F. Mendy 58), Mfuni; Louza (Bove 86), Kayembe, P. Mendy; Maamma, Kjerrumgaard (Doumbia 78), Chakvetadze (Baah 46)
Subs: Baxter, Mullins, Bola, Ince