In continuous casting of steel, the strand is cooled in the upper part of the secondary cooling zone with water sprayed by nozzles towards the strand surface. The water accumulates in the nip of the lower roll of a roll pair, forming a water pool which then drains off towards the ends of the roll. In the present work, the pool height has been measured for the vertical slab region in laboratory experiments. The obtained data are evaluated by dimensional analysis. Equations are given for pool height values in the middle of the roll and at its ends as well as for the pool profile.