Our family of seven goes through a LOT of liquid hand soap, [Foaming soap dispensers haven’t lasted long enough to save us money.] The typical dispenser seems to pump out far more soap than I really need – and young kids sure like to pump the soap out!
I take a clear vinyl-coated twist tie (the kind used to fasten toys to their packaging), twist it two or three times around the stem of the pump (between the spout and the bottle)(enough to cover about half the stem), and twist the ends together tightly.
I’ve done this with shampoo and body wash dispensers as well. We’re still getting enough soap and shampoo to do the job, and we’re wasting far less.