The Uniform Plumbing Code sets the sizes of septic tanks based on the number of bedrooms in a residence. The plumbing code also gives the administrative authority leeway to require higher requirements when the requirements are essential to maintain a safe and sanitary condition. An example is a 3,000 square foot house that has nine rooms (excluding bathrooms) and the builder states it’s only a two-bedroom residence with four bathrooms. A 750-gallon tank is not appropriate for this residence. The County would require a minimum 1200-gallon tank.