Which method is considered uncommon for supplying water from source to customer?

The direct pressure system is considered uncommon for supplying water from source to customer because it relies on a continuous pressurization method, which can often be less efficient and more resource-intensive compared to other traditional methods. This system requires pumps to maintain sufficient water pressure at all times, which can lead to increased operational costs and energy usage.

In contrast, methods such as gravity systems take advantage of natural elevation differences to move water without the need for extensive pumping, making them more energy-efficient for many applications. The distributing reservoir system allows for the storage of water and helps in managing peak demand without having to continuously pump water. Domestic water softeners are used for treating water quality issues, rather than for primary water supply, making them irrelevant to the method of distribution itself but rather a supplementary treatment system.

Therefore, while there are various established methods for water distribution, the reliance on continuous pressure through pumps characterizes the direct pressure system as less common, thus highlighting its distinction compared to more traditional approaches.