I started using water levels in about 1963, helping my Grandfather lay the foundation & basement for our 60'x30' duplex. He used it for keeping the cinder block absolutely level. Laser's would have been nice, but water and hose worked.
With the advent of cheap plastic tubing, like for aquarium air pumps, we moved to using a roll of tubing, a adequate food coloring in the water, and a gallon jug. Didn't work well at lower temps because the hose got stiff. But rolled up small, easy to deploy and very accurate.