A dialysis machine (e.g., a peritoneal dialysis (PD) machine) can include a safety feature that is used to isolate individual fluid lines attached to a disposable cassette. The PD machine can include an interface for a disposable cassette, a plurality of safety mechanisms, and a processor. A plurality of fluid lines are connected to the disposable cassette, and each safety mechanism corresponds to a particular fluid line in the plurality of fluid lines. The processor is configured to detect a hazard condition, such as a loss of power to the PD machine or leak in the disposable cassette, and activate one or more safety mechanisms to isolate corresponding fluid lines connected to the disposable cassette. In one embodiment, the safety mechanisms are spring-loaded clamping mechanisms configured to compress a distensible tube connected to the fluid line. In another embodiment, the safety mechanisms include relay solenoids and/or check valves.