Water tanks on fire apparatus are required to have ________ to stop liquid surges.

The correct answer is that water tanks on fire apparatus are required to have baffles to stop liquid surges. Baffles are internal structures within the water tank that help to control the movement of water as the apparatus is in motion. When a fire truck accelerates, brakes, or turns, the water inside the tank can shift, creating a sloshing effect that could destabilize the vehicle.

By incorporating baffles, the design mitigates the impact of these liquid surges, allowing for better vehicle handling and safety. This is crucial for fire apparatus since quick response times often require sudden maneuvers that could be hazardous if the vehicle becomes unbalanced due to water movement.

Other components like valves, filters, and pumps serve different purposes: valves control the flow of water, filters remove contaminants, and pumps are used to move water from the tank to the hoses. While these are essential for the operation of fire apparatus, they do not specifically address the issue of water surge control, making baffles the critical feature in this context.