Under what condition can non-potable water be reused in household plumbing?

Non-potable water can be reused in household plumbing under the condition that it is treated and meets safety standards. This is crucial to ensure that any water that comes into contact with drinking water supply systems does not compromise public health. The treatment process typically involves filtration, disinfection, and other processes to remove contaminants, thus making the water safe for specific applications, such as toilet flushing or irrigation.

Meeting safety standards is essential to prevent the possibility of contamination that could arise from improperly managed non-potable water. This concept aligns with the guidelines outlined in plumbing codes and regulations, which place a strong emphasis on safety and health, ensuring that any water used in household plumbing adheres to established quality and safety benchmarks.

Other options imply less rigorous standards for the use of non-potable water, which could pose health risks. For instance, reusing it without treatment or limiting it solely to rainwater without proper management disregards necessary safety practices. Additionally, while using non-potable water freely for gardening purposes might sound permissible, it still needs to be assessed against health regulations to avoid potential contamination with edible plants. Thus, the requirement for treatment and adherence to safety standards is the most responsible approach for the safe reuse of non-potable water in household plumbing systems.