To make liquid laundry soap, you will need the following ingredients: grated bar soap, washing soda, borax, and water. Start by grating the bar soap and adding it to a large pot with water. Heat the mixture until the soap is completely dissolved. Next, add washing soda and borax to the pot and stir until dissolved. Finally, add more water to the mixture until it reaches your desired consistency. Allow the mixture to cool and then transfer it to a storage container. Use about ¼ – ½ cup of the liquid laundry soap per load of laundry.