Embodiments of a negative pressure wound therapy systems and methods for operating the systems are disclosed. In some embodiments, a system includes a pump assembly, canister, and a wound dressing configured to be positioned over a wound. The pump assembly, canister, and the wound dressing can be fluidically connected to facilitate delivery of negative pressure to a wound. The pump assembly can present graphical user interface screens for controlling and monitoring delivery of negative pressure. The system can be configured to efficiently deliver negative pressure and to detect and indicate presence of certain conditions, such as low pressure, high pressure, leak, canister full, and the like. Monitoring and detection of operating condition can be performed by measuring one or more operational parameters, such as pressure, flow rate, and the like.