Alteration Septic System OWTS designs are for the alteration of existing sewage disposal systems. Alteration Septic System OWTS designs are appropriate whenever: * Proposed change in the size of an existing Septic System OWTS. * Modification of an existing Septic system OWTS. * A building renovation or change of use of any structure discharging sewage into the Septic System. A “change in size” of an existing Septic system means any physical alteration to your Septic System which will allow the system to accommodate: 1. In the case of a residence, the additional sewage flow resulting from the addition of not more than one bedroom; or 2. In all other cases, an increased flow of sewage in an amount less than or equal to twenty-five percent (25%) of the design flow. Changes in size which will accommodate increased sewage flows resulting from more than one bedroom or in an amount greater than twenty-five percent (25%) of the design flow (approved) must obtain a permit as a New Construction Septic Systems OWTS.