
Hi,
Kadappa stone of 2″ ( 50.8mm ) having its density in the range of 5.0 to 5.4 kg/cm^3 with a water absorption ratio of less than 2%.
After calculation, you may found that at 6-meter height, it is not able to bear the weight of a 500-liter water tank.
Thus, support in the middle must be provided for stability and to increase the bearing strength of kadapa so that it lasts for a long duration.