Dirt.
Detergent Refill 425ml
To reduce plastic packaging further still, fill your empty bottle with refill packs. You can send these back to be reused. 3 packs. 90 loads. 33c per load.
Ingredients: Nonionic Surfactants, Anionic Surfactants, Alkaline Salts, Organic Enzymes, Natural Fragrance, Preservatives