Mobile water supply apparatus are often called:

Mobile water supply apparatus are commonly referred to as water tenders. These vehicles are specifically designed to transport large volumes of water to locations where a traditional water supply might not be available, particularly in rural or remote areas. Water tenders play a crucial role in firefighting operations, especially when access to hydrants is limited or nonexistent.

Water tenders typically have a tank that can hold several thousand gallons of water, along with the necessary pump and equipment to supply water to firefighting operations. Their design enables them to deliver significant amounts of water quickly, providing essential support to fire crews on the ground.

Other terms, such as engines and water wagons, might refer to different types of apparatus or equipment used in firefighting. Engines typically refer to fire apparatus equipped with firefighting pumps and staffed with firefighters, while water wagons can be less common and may not specifically indicate the large water supply capacity that a water tender provides. Portable hydrants are devices used to supply water in areas where a fixed hydrant system is not available, but they do not transport water themselves. Thus, water tenders are the most accurate term for mobile water supply apparatus.