Red Seal Plumbing Practice Exam

Most tank-type water treatment filters work on a _______ flow system during the filtering sequence.

1. up

2. down

3. circular

4. reverse osmosis

The correct answer is: down

Tank-type water treatment filters work on a down flow system during the filtering sequence. This is because the water flows from the top of the tank down through the filtering media, allowing for better contact time between the water and the media. In the up flow system, the water would flow upwards from the bottom of the tank, potentially causing the media to become displaced or creating an uneven flow. The circular flow system is not commonly used in tank-type filters, as it can be more complex and less efficient. Reverse osmosis is a separate filtration process used for removing dissolved solids and is not typically used in tank-type water treatment filters.