CivilTech Studio
Water Tank Design Calculator
Circular and rectangular liquid-retaining tanks — hoop tension, wall moments and crack-control reinforcement per IS 3370 working-stress method.
- Circular and rectangular tanks in one tool
- IS 3370 crack-width reinforcement
- Hoop tension + wall moments
- Base-slab uplift check built-in
- IS 3370 (Parts 1–2):2009
- IS 456:2000
What it does
Everything the check needs, in one pass
A free online water tank design calculator built for practising structural engineers. Enter tank dimensions, liquid depth and soil conditions; the engine computes hoop tension and wall-moment forces, sizes reinforcement per IS 3370 crack-width limits, checks base-slab uplift stability and exports a stamped PDF report with reinforcement schedule.
Circular and rectangular tanks in one tool
Switch between shapes with a click. Circular uses membrane theory (γ·H·D/2); rectangular handles cantilever or propped action.
IS 3370 crack-width reinforcement
Permissible steel stress (Fe250/Fe415/Fe500) and minimum steel ratio (0.24%–0.16%) applied automatically per wall thickness for durability.
Hoop tension + wall moments
Membrane hoop ring tension at the base, vertical bending moment (fixed-base or propped), and direct pull forces all computed and resolved into a single governing reinforcement area.
Base-slab uplift check built-in
Flotation stability is assessed — uplift pressure from groundwater compared to the self-weight of the base slab and stored liquid weight.
Live section diagram and PDF report
A parametric SVG tank section redraws as you type. Export a code-referenced PDF and bar-bending schedule ready for your contractor.
How it works
From inputs to a signed-off result
- Step 1
Enter tank geometry and material grades
Choose circular or rectangular; input liquid depth, diameter or length/breadth, wall thickness, base thickness, concrete grade (M25–M40), steel grade (Fe250/Fe415/Fe500) and bar size.
- Step 2
Run the design engine
The calculator applies IS 3370 permissible-stress formulae: hoop tension T = γ·H·D/2 for circular rings, cantilever moment M = γ·H³/6 for rectangular walls. Reinforcement is sized for crack control and minimum-steel rules.
- Step 3
Review forces, checks and uplift stability
Inspect hoop tension and wall moment (per metre run), required and provided reinforcement areas, concrete direct-tension and base-slab uplift pressure. All checks reported as pass/fail against IS code limits.
- Step 4
Export PDF and reinforcement schedule
Download a stamped design report and bar-bending schedule with your reinforcement summary, design forces and freeboard notes — ready for site approval.
Standards
Checked against the code, clause by clause
Every result cites the clause it came from, so a reviewer can follow the same path you did.
IS 3370 (Parts 1–2):2009
Code for water-retaining concrete structures — permissible stress design, crack control, minimum reinforcement
IS 456:2000
Indian RCC design code — working-stress limits for concrete compression and direct tension
Who it’s for
Where engineers reach for it
Circular overhead tank for G+4 residential
A 6 m diameter, 4.5 m liquid-depth tank on a rooftop — hoop tension and fixed-base vertical moment drive both circumferential and vertical reinforcement.
Rectangular ground-level storage tank
Industrial or municipal tank (10 m × 8 m × 5 m) with shallow groundwater — cantilever walls and a floating-base check ensure the slab stays anchored.
Crack-control design for water-retaining members
Tight permissible-stress limits (IS 3370-2 Table 4) keep crack widths ≤ 0.2 mm — bar spacing and diameter are tuned automatically for durability.
Retrofit and capacity verification
Reverse-engineer an existing tank drawing to check whether it meets updated code limits or changed liquid-level requirements.
FAQ
Questions, answered
Something else? Open Water Tank Design and try it with your own numbers.
Is this water tank design calculator free?
Yes. The core calculator — for both circular and rectangular tanks, all reinforcement sizing, uplift checks and PDF export — is free with no credit card required.
What code standard does it use?
IS 3370 Parts 1 and 2 (2009 revision) for working-stress design, crack control and minimum reinforcement. Permissible concrete stresses follow IS 456:2000 Table 21.
Does it handle circular and rectangular tanks?
Yes. Circular tanks use membrane thin-cylinder theory (hoop tension T = γ·H·D/2). Rectangular tanks are designed as cantilever walls fixed at the base, with optional propped-wall coefficients per IS 3370-4 / Reynolds tables.
How does it compute reinforcement?
Reinforcement is sized for hoop tension (direct stress) and vertical bending moment, then governed by the maximum of demand and minimum-steel ratio (0.24%–0.16% depending on thickness per IS 3370-1 cl. 8.1).
Can it check base-slab uplift / flotation?
Yes. If you specify a groundwater depth, the tool compares hydrostatic uplift pressure to the self-weight of the base slab (the critical empty-tank case). Floatation risk is flagged immediately.
Does it run in the browser and export PDFs?
Yes. It runs in the browser; the design is computed by our calculation engine, which keeps no copy of your inputs, and nothing is stored in your account unless you save it. Export a code-referenced PDF report and bar-bending schedule in one click.
Open Water Tank Design and run your numbers
Circular and rectangular liquid-retaining tanks — hoop tension, wall moments and crack-control reinforcement per IS 3370 working-stress method.
Get 10 free credits — no card required
Sign up to save projects, export PDFs, and access all design tools.