A:
My old Hoover was purchased when you had to put the cleaning solution into the clean water tank. If you wanted to rinse with water alone, you either had to use up the soapy water or dump it out before rinsing and refilling the tank with water only.
I recently purchased the Hoover FH50150 and am very happy with my purchase. This model allows you to keep the cleaning solution separate so you can switch to rinse with water only before continuing on to shampoo another area.
The plus to adding solution directly to the clean water tank is that you control the cleaning solution to water ratio. You could use less product to clean areas that have little foot traffic or mix for a stronger cleaning solution for high traffic/problem areas.