IS 3370:1967 Part 4 is the Indian Standard (BIS) for concrete structures for storage of liquids - code of practice - design tables. IS 3370 Part 4 provides comprehensive design tables for calculating bending moments, shear forces, and hoop tensions in concrete liquid retaining structures. It includes coefficients for both circular and rectangular tanks subjected to hydrostatic loading under varying support conditions.
Provides design tables for use in conjunction with other parts of IS 3370 for concrete structures for liquid storage.
Key reference values — verify against the current code edition / project specification.
| Reference | Value | Clause |
|---|---|---|
| Subject | Design tables/coefficients for liquid-retaining structures | Scope |
| Use | Moment/shear coefficients for walls & tanks | Application |
| Edge conditions | Coefficients by support/edge fixity & aspect ratio | Tables |
| Read with | IS 3370 Part 1/2 (used together) | Cross-ref |
BIM-relevant code. See the BIM Hub for ISO 19650, IFC, and LOD/LOIN frameworks used alongside it.
IS 3370 (Part 4):1967 (current 2009 edition) provides Design Tables for Liquid-Retaining Structures — pre-calculated tables that simplify the design of standard water-retaining concrete structures (cylindrical and rectangular tanks).
Use it when: - Designing standard cylindrical / rectangular water tanks — service reservoirs, underground sumps, swimming pools, sewage treatment tanks - Quick preliminary sizing of liquid-retaining structures before detailed analysis - Verifying detailed FEM analysis results against simple table-based comparison - Designing standard sizes for water utility infrastructure (most municipalities follow standard tank dimensions for procurement convenience)
The IS 3370 series: - IS 3370 Part 1:1965 (now 2021) — General requirements - IS 3370 Part 2:2009 — Reinforced concrete structures - IS 3370 Part 3:1967 — Prestressed concrete structures - IS 3370 Part 4:2009 (this code, updated from 1967) — Design tables
Design philosophy: water-retaining structures need to be: - Watertight (no leakage; design constrains crack width) - Structurally adequate (carry water pressure + dead loads + wind + temperature) - Durable (long-life service; resistant to chemicals, atmosphere)
Traditional design used uncracked-section analysis (Working Stress Method) — limit tensile stresses in concrete to prevent cracking. IS 3370:2009 introduced limit-state design with crack-width limit — typically 0.2 mm crack width for water-retaining structures.
The design tables in Part 4 give pre-calculated reinforcement requirements for standard tank geometries — saving detailed calculation effort for routine work.
Cylindrical tanks (Clause 3 + Tables 1-3):
For cylindrical tanks of various: - Diameter (typically 2-30 m) - Height (typically 2-20 m) - Wall thickness (250, 300, 400 mm typical) - Concrete grade (M25-M40) - Steel grade (Fe 415, Fe 500)
Tables provide: - Hoop reinforcement (horizontal): bars to resist circumferential tension from internal water pressure - Vertical reinforcement: bars to resist bending from base fixity + temperature / shrinkage - Distribution reinforcement: for crack control
Hoop reinforcement formula for cylindrical tanks: ``` T_h = γ × H × D / 2 (per metre height) ``` where γ = water unit weight (9.81 kN/m³), H = water depth from top, D = tank diameter.
For a 10 m dia × 5 m height tank: max hoop tension at base T_h = 9.81 × 5 × 10/2 = 245.25 kN/m.
At allowable stress 100 N/mm² for Fe 415 (per IS 3370 Working Stress) → required steel = 245,250 / 100 = 2,452.5 mm²/m → provide 20 mm bars @ 125 mm c/c or similar.
Rectangular tanks (Clause 4 + Tables 4-6):
For rectangular tanks with: - Length, breadth, height (typically L:B:H = 1.5 to 3 typical) - Wall thickness varying along height - Concrete + steel grades
Design approach: - Walls behave as vertical cantilever from base (if simply supported at base, fixed at floor) - Or two-way slab for thinner walls / shorter spans - Tables give bending moments at corners + mid-spans for various aspect ratios
Underground tanks add: - Earth pressure on outside (when empty): K₀ × γ_soil × H - Hydrostatic pressure from groundwater (when below water table) - Surcharge effects (vehicular loads above ground)
Floor design (Clause 5): - Floor slab usually supported on column grid (for large tanks) or directly on prepared ground - Reinforcement based on bending moments under hydrostatic pressure from above + ground reaction from below
Problem: 100 m³ underground rectangular tank for residential complex; height limited to 3.0 m due to space; L × B × H to be determined.
Step 1 — Tank geometry: V = L × B × H = 100 m³; H = 3.0 m → L × B = 33.3 m² For square-ish aspect: L = 6.0 m, B = 5.5 m, H = 3.0 m. Effective volume = 6 × 5.5 × 3 = 99 m³ ≈ 100 m³ ✓
Step 2 — Walls: Maximum hydrostatic pressure at base = γ × H = 9.81 × 3.0 = 29.43 kN/m²
For Long wall (6 m × 3 m): Vertical cantilever with base fixity. Max bending moment at base = γ × H³ / 6 = 9.81 × 27 / 6 = 44.1 kN-m/m (Working stress moment for design with FoS)
For Short wall (5.5 m × 3 m): similar with adjusted L:H ratio.
Step 3 — Wall thickness: For cracking-controlled design: thickness ≥ 200-250 mm typical for 3 m height. Provide 250 mm wall thickness (allows 25 mm rebar at 80 mm c/c with proper cover).
Step 4 — Reinforcement (per IS 3370 tables / direct calc): For M_design = 44.1 kN-m/m, d = 250 - 45 - 8 = 197 mm, concrete grade M30: - M_design / b·d² = 44,100,000 / (1000 × 197²) = 1.137 MPa - From Fe 415 design tables: A_st ≈ 0.30% = 591 mm²/m - Minimum reinforcement per IS 3370 = 0.35% (each face) → 875 mm²/m on inner face - Use 0.35% governing → A_st = 875 mm²/m vertical at inside face
Provide 16 mm @ 200 mm c/c (A_st = 1005 mm²/m) ✓
Hoop bars (horizontal) similar calculation for short-wall direction.
Step 5 — Floor: Floor supports water column above (29.43 kN/m² at center) + dead load. For 6.0 m span, use beam-strip analysis OR direct two-way slab analysis. Provide reinforced concrete floor with 200 mm thickness; reinforcement per moment + minimum requirements.
Step 6 — Roof: Usually accessed via manhole; not designed for vehicular load unless underground. Provide 100-150 mm RCC roof with normal slab reinforcement.
Step 7 — Construction details: - Continuous water-stop at all construction joints - Drying-shrinkage joints (saw-cut) if pour > 6 m linear - Curing minimum 14 days - Hydrostatic test before commissioning
1. Using IS 456 minimum reinforcement — water-retaining structures need MORE reinforcement (≥ 0.35% each face, each direction) than IS 456 minimum. Many designers default to IS 456 and have cracking issues post-commissioning.
2. Mixing working-stress and limit-state methods inconsistently — IS 3370 Part 4 tables historically based on Working Stress (1967 edition); 2009 edition has limit-state tables. Specify which approach is being used; don't mix factors.
3. Forgetting water-stop at joints — every horizontal joint (wall-to-base, lift-to-lift) needs continuous water-stop. Sites that skip this for cost have post-commissioning leakage issues.
4. Insufficient cover (< 45 mm) — water-retaining structures need 45+ mm cover per IS 456 Table 16 + IS 3370. Many sites use 25-30 mm for cost-saving; rebar corrosion + spalling within 5-10 years.
5. Inadequate curing duration — water-retaining concrete needs 14-21+ days curing (vs 7 days for ordinary RCC). Short curing causes plastic shrinkage cracks that compromise watertightness.
6. Mix design without proper trial — water-retaining concrete needs balanced workability + low W/C + adequate cement + appropriate SCM. Test trials are mandatory.
7. No hydrostatic test before commissioning — IS 3370 Part 4 prescribes water-fill test (fill to capacity; let stand 7-14 days; measure leakage). Acceptance: ≤ 5 mm drop over 7 days. Many projects skip this; problems found 6 months later.
8. Backfilling external sides too early — for partially / fully buried tanks, external backfill applies lateral pressure. If applied before concrete has reached design strength + proper curing, walls deflect inward; cracking ensues.
9. Skipping waterproofing admixtures — crystalline waterproofing admixtures (e.g., Xypex, Penetron) reduce concrete permeability significantly. Cost premium: ~5-8% on concrete; saves substantially in repair / lifecycle.
10. No drainage / weep at low point — even well-designed tanks occasionally seep. Provide weep at lowest point of tank exterior + drainage channel to evacuate. Without weep, seepage damages adjacent foundations / building.
IS 3370 Part 4 is a historical foundation of Indian water-retaining structure design. The 1967 original is now superseded by the 2009 revision which: - Added limit-state design tables - Updated for higher concrete grades (M35, M40) - Refined crack-width acceptance criteria - Added deeper underground tank considerations
For routine projects: IS 3370 Part 4 tables are a useful shortcut for standard tank designs. Most Indian water-supply infrastructure (service reservoirs, underground sumps) is designed with these tables.
For complex / large tanks: detailed FEM analysis is preferred: - Cylindrical tanks > 20 m dia - Rectangular tanks > 10 m × 10 m - Buried tanks with complex earth-pressure conditions - Tanks subject to dynamic loads (seismic, vehicular)
Indian water utility reality: - Major water-supply projects (JJM, AMRUT 2.0): typically use IS 3370 Part 2:2009 (limit state) + Part 4 design tables for standard reservoirs; supplemented by FEM for complex geometries - Residential / commercial buildings: underground sumps designed with IS 3370 Part 4 tables; rooftop tanks usually polymer (IS 12701) - Industrial water tanks: depending on size + chemistry, may use IS 3370 (water + general) OR specialized codes (IS 7720 chemical-resistant linings, etc.)
Design software: most Indian structural firms use STAAD Foundation Advanced, SAFE, CSiCol, or ETABS for tank design. These automate the IS 3370 calculations + provide reinforcement detailing. Hand calculation with IS 3370 Part 4 tables is now reserved for preliminary sizing + verification.
Quality assurance: - Pre-construction: verify design meets IS 3370 + IS 456 requirements - During construction: monitor curing, water-stop installation, joint preparation - Post-construction: hydrostatic test (mandatory; documented per IS 3370 Part 4 acceptance criteria) - Service: periodic inspection (every 5-10 years); check for cracks, surface deterioration
Common project failures: - Leakage at construction joints: 40-50% of post-commissioning leakage; preventable with proper water-stop installation - Surface efflorescence: 30-40% of issues; from inadequate curing + moisture migration - Cracks at corners: from differential settlement, drying shrinkage at restraints; requires post-construction repair with epoxy injection or surface waterproofing - Foundation settlement: rare but catastrophic; needs foundation design per IS 1904 + soil investigation
For premium projects (water-treatment plants, storm-water tanks, large municipal reservoirs): - Use IS 3370 Part 2:2009 (limit state) + Part 4 (tables for verification) - Add crystalline waterproofing admixture (5-8% cost premium; substantial leakage prevention) - Mandate 14-day curing minimum + curing protocol documentation - Hydrostatic test per IS 3370 Part 4 acceptance criteria - 5-year warranty on watertightness from contractor
This design discipline is critical: water-tank cracking can cost ₹50,000-5,00,000 per cubic metre to repair, vs ₹5,000-15,000 per cubic metre for original construction. Pay the upfront premium for quality.