Which of the following is not one of the NFPA's 20 technical rescue specialties?

The choice not considered one of the NFPA's 20 technical rescue specialties is standing water. NFPA 1670 outlines various rescue disciplines that fall under technical rescue specialties, which include specific categories such as rope rescue, structural collapse rescue, and others that are focused on distinct areas of emergency response.

Tower rescue and rope rescue are both specialized areas that are recognized due to their unique challenges and the need for specialized training and equipment. Structural collapse rescue is similarly distinct, addressing the specific protocols and techniques needed in scenarios where buildings or structures have failed.

In contrast, standing water may refer to a condition encountered during rescue operations but does not constitute a standalone technical rescue specialty as defined by the NFPA. Instead, rescue operations involving water tend to fall under categories like water rescue or swift water rescue, which focus on moving water scenarios rather than standing water itself. Recognizing the difference helps ensure that personnel are trained specifically for the environment and variables they will encounter in their rescue efforts.