This model presents the structural design of a waterproof "white tank" structure of a reinforced concrete foundation for a multistory residential building, developed in a Master's thesis. It integrates a foundation slab with piles to fulfill both ultimate and serviceability limit state requirements. The analysis of internal forces was carried out using RFEM software combined with the SOILIN add-on module, which simulates soil–structure interaction and considers the early-age concrete behavior. Detailed reinforcement layouts and dimensional configurations ensure the structure’s waterproof integrity.