Nonconforming lot. Any lot existing on the effective date of this chapter, as amended, that has an area or width less than that specified in Schedule II hereof, may be used for any purpose permitted in the district but there shall be compliance with all other regulations (use, yards, height, etc.) prescribed for the district. Notwithstanding the above, if the owner of such undersized lot also owns adjacent land that could be used to bring the undersized lot into compliance, this should be done when feasible. Approval of new construction or rebuilding on any undersized lot in the R-3 District shall be subject to approval of the proposed sewage disposal system.