Abstract: A fluid-tight tank is composed of a plurality of separate components. Each component is preferably formed from cement and provided with an interior region having a circular cross-section. Each component has a plurality of chase ways extending throughout its length. Post-tension cables are routed through these chase ways and are tightened so as to compress the components together so they act as one integral unit. Each component is has an annular flange-like protrusion and/or recess so that adjacent components can be aligned with one another while maintaining the circular cross-section quality throughout the entire length of the interior region. One or more of the components can be provided with a wall to separate one interior region with another.