Circular tank is considered as the easiest form of water tank. The lesser amount of material is needed for maintaining the similar amount of storage. Besides, due to its circular shape it does not contain any corner and it can be water resistant. It is very cost-effective for lesser storage of water up to 20000000 liters and with diameter in the range of 5 to 8 m. The intensity of the storage is among 3 to 4 m. The side walls are built up for hoop tension and bending moments.

By going through this construction video tutorial presented by S.L. Khan (the renowned engineer), one can learn how to work out the materials for circular water tank. In this video the calculation is made on the basis of the given example:-

Example: Calculate cement, sand, crushed stone and steel for a specified water tank.

The diameter of first circle is given as 4 meter, the diameter of second external circle is 15 cm and diameter of third external circle is 10 cm. R.C.C. of the base is 15 cm and the ratio is 1:2:4. Here, the ratio of PCC is 1:2:4. R.C.C of the slab is 10 cm and the ratio is 1:2:4. There is also a circular shaped manhole and its diameter is 60 cm.

Lowest Reinforcement for Water Tank

Lowest reinforcement necessary for 199mm thick sections is 0.3 % of the area of concrete section that is decreased linearly to 0.2% for 450 mm thick sections. In case of floor slab for tank leaning on ground the least reinforcement should not be under 0.3% of the gross sectional area of the floor slab.

If the density of the section (wall, floor or roof slab of the tank) is calculated as 225 mm and over two layers of reinforcing steel shall be arranged, one near each of the section to make up the minimum reinforcement requirements.

On the basis of the above dimensions, the calculation is made.
Watch the following video to get the detailed process for calculation :

Video Courtesy : SL Khan