A container (10) comprising a plurality of compartments (A, B, C) separated by compartment dividers (6), and an inlet connector (3) for receiving a liquid via a connection tube (2). The compartment dividers rupture when a sufficient pressure is applied by a liquid or gas introduced into the container (10) through the inlet connector (3). Some of the compartments comprise powder, which dissolves at the introduction of liquid into the container. A system, process and use in the field of dialysis are also disclosed.