Which feature do most water systems have that allows them to supply water under pressure even if pumps fail temporarily?

Most water systems incorporate elevated water storage towers as a key feature that allows them to supply water under pressure even in the event of temporary pump failures. These towers operate on the principle of gravity. When water is stored at a height, the force of gravity facilitates the movement of water down through the system, maintaining consistent water pressure in the distribution lines.

In an emergency situation, if pumps were to fail, the water stored in these elevated tanks can still be delivered to consumers, ensuring that there is a reliable water supply for firefighting, drinking, and other essential uses. This design also allows for the balancing of water demand during peak times, as the gravitational potential energy stored in the water can be harnessed to maintain flow rates.

The other options, while they might sound plausible in different contexts, do not serve the dual purpose of providing sustained water pressure during pump failures along with a fail-safe mechanism like that of elevated storage.