If you don't have any hair to wash, that's probably about as zero waste as you can get for hair care. For those of us with tresses that need cleaning, I recommend this bar of all-natural shampoo from J.R. Liggett that I recently stumbled upon at my local coop. The Original Formula bar is made from all natural ingredients: olive oil, coconut oil, castor oil, sunflower oil, organic palm kernel oil and rose oil. They do not use GMOs or traditional palm oil which destroys ecosystems and negatively impacts producer communities. The 'palm kernel oil' ingredient they use is 'Roundtable for Sustainable Palm Oil' (RSPO) certified. Read more about RSPO here and here. This product scores high on sustainable zero waste packaging as well with a simple recyclable paper wrapping instead of a plastic bottle and cap that may or may not be recyclable in your area. Additionally, the concentrated formula -- no water! -- minimizes the product volume and weight as compared to traditional shampoos which saves on the resources required for storage and transportation of the product. Thanks J.R. Liggett for an uncomplicated product and effective design!