Systems, apparatuses, and methods for instilling fluid to a tissue site in a negative-pressure therapy environment are described. Illustrative embodiments may include a pneumatically-actuated instillation pump that can draw a solution from a solution source during a negative-pressure interval, and instill the solution to a dressing during a venting interval. A pneumatic actuator may be mechanically coupled to a disposable distribution system that can provide a fluid path between the solution source and a distribution component. A bacterial filter may be disposed in the fluid path between the actuator and the distribution component to prevent contamination of the actuator during operation. The distribution system may be separated from the actuator and disposed of after operation, and the actuator may be re-used.