A water­mark is a notice (e.g.,Draft,”Con­fi­den­tial”) that’s printed in the back­ground of a page. Often in six-inch let­ters. Diag­o­nally. In red.

Water­marks inter­act poorly with the text, cre­at­ing visual noise that dis­tracts from read­ing. (It’s a vari­a­tion of the prob­lem noted in rules and borders.) Also, water­marks can darken con­sid­er­ably when pho­to­copied, aggra­vat­ing the prob­lem.

It’s hard to make water­marks look good. Bet­ter to con­vert the water­mark text to a notice within the header or footer.