DRY GOODS

I don't know why it took so long for me to realize such an obvious thing: whenever possible, buy the powdered or dry form of items for which it really doesn't make much difference.
Purchasing the water content of diluted ingredients just doesn't make sense.

The density of water is about 60 lb / cubic foot (about 1000 kg / cubic meter).

1 gallon weighs about 8 lb (3.8 kg) and takes up 231 cubic inches (3,800 cubic centimeters)

Think of all the energy spent in transporting mostly water (80% of liquid laundry detergent, according to this article).

  

Laundry

Some will argue that powder leaves unmelted residue on clothes.
That is very true and there is a very simple fix: dissolve the laundry powder yourself before adding to the wash. I use an empty yogurt container and a used plastic knife (I usually dislike those intensely but they are perfect for this use). A few stirs and voila! you're done and it was fun.

Bonus: if it's not liquid, it doesn't need to come in a plastic bottle. Your waste can be reduced to just a cardboard box. One less landfill issue to worry about.

Food 

Recently glossed over a rather scathing article about almond milk and other plant-based milks (which are my bread and butter, pun intended). They are right about the purchasing of mostly water. You know what? One can also buy powdered almond, coconut, etc. milks. The box seems expensive because it's so much at a time once dissolved, but I bet it's worth the investment.

Paint

I love Milk Paint which comes in small packages of powdered color (pigments mixed with milk protein and lime) to which you just need to add water. Seems like a safe and environmentally friendly option.

So yeah. Dry goods.