Pools used for swimming or bathing shall be in conformity with the requirements of this article; provided, however, that these regulations shall not be applicable to any such pool less than 24 inches deep or having a surface area less than 250 square feet, except when such pools are permanently equipped with a water-recirculating system or involve structural materials. For purposes of this article, pools are classified as "private swimming pools" or "public and semipublic swimming pools," as defined in § 154-133.