Most people will just fill the dishwasher’s soap container, or fill the cup that came with the box in the case of powdered soap, and that’s it. Few are those that have read the instruction manual of the dishwasher or even read the instructions on the soap container.
What if you could reduce that mountain by a significant amount (maybe by half or more, depending) without affecting how clean your dishes are? Just read your dishwasher’s instruction manual and the instructions on your soap to find out how much soap you really need.
How effective soap is depends on the ‘hardness’ of your water (how much dissolved minerals are in it). If your water is very hard, you might need to actually fill the soap cup completely, but in most other cases, a lot less soap is required. In fact, with soft water, as little as one tablespoon (or less with concentrated soap) is required.
Don’t forget your hands sometimes!