A modular panel made of plastic material for manufacturing pool walls comprises: a generally rectangular main body of which a first surface is intended for being oriented toward the inside of the pool, the lengths of the main body defining a reference plane; a complementary body capable of being attached to a second surface of the main body and defining a hollow column intended for receiving concrete, wherein the first surface has an initial convex transverse curve on the width of the main body in a plastic injection mold, the maximum amplitude of the transverse curve relative to the reference plane being selected to compensate for all or part of the deformations that occur between the removal from the mold and the setting of the concrete, in the transverse and longitudinal directions.