What are isolation valves used for in a water distribution system?

Isolation valves play a critical role in a water distribution system by allowing for the isolation of specific sections of the system for maintenance or repairs without disrupting the entire distribution network. This is essential for ensuring that water supply can be maintained to other areas while work is being performed.

By using isolation valves, operators can shut off the flow of water in a particular segment, facilitating the safe inspection, maintenance, or replacement of pipes, fittings, or other components. This not only supports routine upkeep and emergency repairs but also helps in managing the operational efficiency of the water distribution system.

The other choices, while related to the functioning of water systems, do not accurately describe the primary function of isolation valves. They do not serve to increase water pressure, control the quality of water, or measure flow rates—functions typically associated with pumps, water treatment processes, and flow meters respectively. Instead, the primary function remains focused on maintenance and operational integrity, which is why the answer aligns with the correct identification of isolation valves' usage.