Washberry soap nuts are the dried fruit of the Sapindus Mukorossi tree.
You can use them in your washing machine, dishwasher and to make your own detergent.
These are what they look like. Little, sappy looking berry nuts.
They are natural so you aren't putting harmful chemicals down the drain.
Also, if you want to re-use your grey water you know you won't be putting poisons onto your gardens.