With the resistance lever set at the highest level, check that the tank is filled to the correct level, as shown by the tank level decal on the lower side of the tank.
NOTE: Do not fill the tank beyond the maximum indication – refer to the tank level decal on the lower side of the tank.
Check that the upper filling cap is tightened (this can be done with a large coin or a flathead screwdriver to seal up and prevent leaking). Tightening the cap by hand-only may not seal the cap, and lead to leaking. The cap fits in the hole if you have the o-ring snug against the tank, it will then not leak.
To test, fill up the tank, seal the cap, and row for five minutes. If there is any water pooling, you will need to tighten and/or adjust the o-ring to sit correctly in the final groove of your tank cap.
NOTE: The lower tank plug is permanently sealed.