First Officer reported receiving a Stall Fail caution message on takeoff roll. Flight crew rejected takeoff and returned to gate where maintenance drained water from the standby pitot system and returned the plane to service.

Narrative

Began the flight as normal. No caution or warning messages. We were cleared to line up and wait Runway XL at ZZZ (I was Pilot Flying). Once cleared for takeoff; I advanced the throttle and as soon as the plane began accelerating; we immediately got a STALL FAIL caution message. We must have only moved a number of yards and couldn't have exceeded 10-15kts. I pulled the throttles back to idle and we informed Tower we were discontinuing take off. A soon as the throttle was back to idle the caution message disappeared.We were advised to pull off on either [Taxiways] 1 or 2 and turn right onto [Taxiway] 3. After informing Tower that we had a caution message. They asked if we needed assistance; and we said no but would need to hold position off the runway to assess.The Captain called Maintenance and explained that we had the stall fail on takeoff roll; and our speed; as well as the fact that the message had disappeared.We were advised to do a stall test; so I pushed the stall button and the test ran through as normal. Maintenance asked us if anything out of the ordinary happened during the test - to which we said no. We were advised that we were OK to try again to depart.We advised ATC who sequenced us back to hold short of XL on [Taxiway] 4. We were again cleared to line up and wait. Everything was normal as before. After being cleared for take-off; I advanced the throttle and once again immediately got the stall fail caution message. We discontinued the take-off same as the first attempt stopping in the same amount of distance and advised ATC we were going to head back to the gate.When we returned to the gate; Maintenance came out and said that the standby pitot tube piping was full of water. They drained the water and tested the system and returned the plane to service.We were then able to complete the original flight as planned with no further issue. We didn't see the STALL FAIL caution message again - during takeoff or any other phase of flight.