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