Exhibit No. 18



  To the Board of Directors
  of Calgon Carbon Corporation



  October 19, 1998

  Dear Directors:

  We have been furnished with a copy of the Corporation's Form 10-Q for the
  quarter ended September 30, 1998.  Note 5 therein describes a change in the
  method of determining the cost of inventories from the last-in, first-out
  method to the first-in, first-out method.  It should be understood that the
  preferability of one acceptable method of inventory accounting over another
  has not been addressed in any authoritative accounting literature and in
  arriving at our opinion expressed below, we have relied on management's
  business planning and judgment.  Based upon our discussions with management
  and the stated reasons for the change, we believe that such change represents,
  in your circumstances, the adoption of a preferable alternative accounting
  principle for inventories in conformity with Accounting Principles Board
  Opinion No. 20.

  We have not made an audit in accordance with generally accepted auditing
  standards of the financial statements of Calgon Carbon Corporation for the
  three-month or nine-month periods ended September 30, 1998 or September 30,
  1997 and, accordingly, we express no opinion thereon or on the financial
  information filed as part of the Form 10-Q of which this letter is to be an
  exhibit.

  Yours very truly,
 


  PricewaterhouseCoopers LLP