Abstract: A negative pressure wound therapy device can include one or more fluid detection systems. A canister fluid level detection system can incorporate various fluid detection devices to communicate data relating to the fluid level of the canister. In some cases, a negative pressure wound therapy device can include a device housing, a negative pressure source, and a canister configured to be in fluid communication with the negative pressure source. The canister can include a canister housing configured to store fluid aspirated from a wound, a cap connected to the canister housing, and a fluid level sensor supported by the cap. The fluid level sensor can be configured to detect a completed electrical circuit when the fluid aspirated from the wound comes into contact with the sensor. An electronic circuitry can be configured to detect a state of the sensor and provide an indication of a status of the canister.