Hi. The cistern on the back  porch of the Moser House (1880s-1920) 
(3BE311 in NW Arkansas) had a sand filter on one side at the 
mouth.  The overall shape was a keyhole with the round mouth of the 
cistern being the "barrel" of the key and the filter box the 
"tang".  The filter box was 2 bricks thick on the sides, one brick 
wythe thick on the base, full of sand, and connected to the cistern 
mouth by a brick tunnel covered with window screen.  The cistern and 
filter box were covered by a wooden box of course.  An informant said 
the drainpipe off the roof fed directly into this filter box.  See 
http://www.uark.edu/campus-resources/archinfo/atumoser.html Fig.6 for 
Fea 4. Or buy the Moser report, 1986, Arkansas Archeological Survey 
Research Series No. 26, via the same web site.  Nahhh, just visit the web site.

At 11:45 PM 4/8/2008, you wrote:
>Hello all,
>
>Has anyone encountered red brick filters inside of water cisterns?
>
>In the cistern I have been studying, slightly off center on the 
>floor is a solid block of cemented bricks.  It measures 
>approximately 49" high, and 2 bricks wide, and 3 1/2 bricks 
>long.  One brick width protrudes down the sides of the 
>construction.  On the top is a place built up of 1 brick wide into 
>which the original ferrous pipe was inserted.  There is no evidence 
>of any opening anywhere.
>
>Thanks,
>S. Walter

Leslie C. "Skip" Stewart-Abernathy, Ph.D.
Arkansas Archeological Survey
Winthrop Rockefeller Institute
Petit Jean Mountain
1 Rockefeller Drive
Morrilton, AR 72110
501 727-6250