IS 11244:1985 is the Indian Standard (BIS) for design and construction of elevated reinforced concrete water tanks. This Indian Standard outlines the code of practice for designing and constructing elevated reinforced concrete water tanks. It specifies the materials, loads (including hydrostatic, wind, and seismic), design principles based on the working stress method to ensure water tightness, and construction and testing procedures.
Covers recommendations for the design and construction of elevated reinforced concrete water tanks.
BIM-relevant code. See the BIM Hub for ISO 19650, IFC, and LOD/LOIN frameworks used alongside it.
| Parameter | IS Value | International | Source |
|---|---|---|---|
| Minimum Grade of Concrete | M20 (20 N/mm²) | 4,000 psi (approx. 28 N/mm² or M28) | ACI 350-20 |
| Maximum Permissible Crack Width (Liquid Face) | 0.2 mm | Typically 0.1 mm (0.004 in) for severe exposure, though 0.2 mm is a limit for less critical cases. | ACI 350-20 / EN 1992-3 |
| Permissible Steel Stress in Direct Tension (Serviceability) | 150 N/mm² (for Fe415/HYSD bars) | Not directly limited; crack width is calculated. Equivalent stress is often around 200 N/mm² but depends on bar size and spacing. | ACI 350-20 |
| Minimum Concrete Cover (Water Face) | 25 mm | 50 mm (2 inches) | ACI 350-20 |
| Minimum Wall Thickness | 100 mm | Recommended minimum 200 mm (8 inches), 300 mm (12 inches) preferred. | ACI 350-20 |
| Minimum Reinforcement for Walls (% of gross area) | 0.3% reducing to 0.15% (for thickness 100mm to 450mm) | Typically 0.5% for temperature/shrinkage (Grade 60 rebar), reducible for thick sections. Varies by calculation. | ACI 350-20 |
| Freeboard (minimum) | 200 mm | 300 mm (12 inches) or more depending on tank size and wind conditions. | AS 3735-2001 |