Like a home septic system, a dog septic tank treats solid waste, breaking it down into liquid and releasing that liquid in the soil, where microbes purify it. To install this pet waste disposal system, dig a hole in your yard, place the container in the ground and cover it with the lid. When needed, drop in dog waste, add water and tablets or digestive powder for dogs in the instructed amounts. Make sure to use a pet waste digester that is environmentally friendly. Look for formulas specially made with bacteria and protein enzymes meant to break down dog waste.