One substitution for dishwasher detergent is to mix regular dish washing soap with water. Another option is making homemade dishwasher detergent out of borax, washing soda, citric acid and kosher salt.
To substitute dish washing soap for dishwasher detergent, people need to mix the solution at a ratio of 2 teaspoons of soap to 1 gallon of water. Fill the soap dispenser cup with this solution.
Huffington Post suggests an alternative to that recipe. People can drip three drops of dish washing soap into the dishwasher cup and add enough baking soda to fill the cup two-thirds of the way. They then use kosher salt to finish filling the cup. The baking soda counteracts the smell from the dishes, and the kosher salt scrubs food away.
To make natural dishwasher soap, people mix 1 cup of borax, 1 cup of washing soda, 1/2-cup of citric acid and 1/2-cup of kosher salt in a plastic container. They add 1 tablespoon of the mixture to the dishwasher cup.
It's important never to replace dishwasher detergent with dish washing soap at a 1-1 ratio. Dish washing liquids contain too much sudsing agents for a dishwasher, resulting in an overflow of suds from the dishwasher. Likewise, the soap does not rinse from the dishes. If this happens, switch on the dishwasher's rinse-only cycle, and continue running the dishwasher until the suds are gone.