Mix together, use one-three tablespoons per load, it will not seem like enough, but it is more than enough. You need to get the bar soap ground down as finely as possible, I grate mine then run it though the food processor with the blade attachment. I grate up one bar of soap, measure it, then add equal parts of washing soda and borax. Omit the borax if your gray water goes out onto plants that you wish to keep, borax will kill plants, your laundry will still come out clean without the borax.