Sava denied Derry striker Rory Patterson on a litany of occasions as the Candystripes bossed the opening period.
Having saved a Patterson free-kick in the 11th minute, the keeper then diverted another shot from the striker over his crossbar in the 29th minute.
But from the resultant corner, the home side went in front.
Kevin Deery floated the ball into the danger area and as the Drogheda defence failed to clear, Ryan McBride rose at the back post to head the ball firmly home.
Sava saved Drogheda again in the 55th following a superb Derry City passing move on the left. Barry McNamee played the ball into Mark Griffin and the keeper was equal to the effort in the 64th minute.
But those failures in front of goal would cost the home side dearly when Drogheda equalised with 10 minutes remaining.
Drogheda won a corner on the right and Mick Daly glanced the ball home at the near post.
DERRY CITY: Doherty; Madden, McBride, S. McEleney, B. McNamee; Molloy; Deery (Crawley, 39), Higgins; Griffin (Houston, 71),
Patterson, Rafter (Duffy, 81).
DROGHEDA UNITED: Sava; Gannon (Hynes, 72), Grimes, Byrne, Hand (Foley, h/t); Rusk, O’Connor, Daly, G. Brennan; O’Brien, Cassidy (R. Brennan, 65).
Referee: T. Tomney (Dublin).