Single-use plastic bottles exist because we buy a lot of products that are mostly water. The latest company to realize this is stupid (since most of us already have water on tap in our homes) is Seventh Generation, a manufacturer of cleaning products.
"The plastic lifecycle is impacting people's health with microplastics even appearing in our bodies," the company writes. (This summer it was discovered that microplastics have even found their way into fruits and vegetables.) "Yet, the global demand for plastic is growing and a driver of the fossil-fuel industry. We see it as our responsibility to source sustainably and break the reliance on the plastic economy."
To do this, the company identified the reason why plastic is the go-to packaging material: Because it makes an excellent moisture barrier. Get rid of the water, and you not only obviate the need for a moisture barrier, but you make the product lighter, which means shipping it requires less resources.