 because , while storm drains are designed to accept surface runoff from streets, combined sewers were designed to also accept sewage flows from buildings with basements  .
<meaning-changed>  because , while storm drains are designed to accept surface runoff from streets, combined sewers were designed to also accept sewage flows from buildings with basements  .
 because , while storm drains are designed to accept surface runoff from streets, combined sewers were designed to also accept sewage flows from buildings with basements , in addition to receiving surface runoff from streets .