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Water-Sump / Tank Calculator — Capacity, Materials & Cost (Instant)
This interactive calculator sizes your **rectangular or cylindrical** water tanks, computes **storage capacity**, estimates **concrete**, **rebar**, and **waterproofing**, and builds a **cost summary** with editable rates for **India / US / UK**. It supports **multi-compartment** sumps, **SI / Imperial** units, **reverse mode** (size from target volume), **standards presets** (IS 3370, IS 456, ACI 350, BS 8007), and a **printable HTML report** with KPIs and a detailed table.
How it works (in plain language)
- Geometry: Choose shape → enter inside dimensions (L, B, H) and freeboard. Reverse mode lets you enter a target capacity and it solves the height.
- Materials: The tool derives base slab, walls, and top slab concrete volumes; planner-level rebar densities are prefilled by standard profile and are **user-editable**.
- Waterproofing: Select internal/external/both sides; overlaps are included via a % allowance.
- Costing: Enter local unit rates (auto-prefilled by country). A markup % applies to the materials subtotal.
- Report: One click generates a clean, printable HTML report with project metadata, KPIs, breakdown table, assumptions, and formulas.
When to use this
- Estimating **underground sumps** for buildings, villas, and campuses.
- **Overhead tanks** with rectangular compartments (supports top slab).
- Quick checks during design development, BOQs, and tender support.
Useful companions
Concrete mixes & multi-element BOQ → Concrete Calculator
Rebar cutting lists → BBS Calculator
Site grading/backfill → Cut-&-Fill Calculator
Inlet/outlet headloss → Pipe Design Calculator
Codes & Standards (presets)
- IS 3370 (with IS 456) – default for India
- ACI 350 – environmental engineering concrete structures
- BS 8007 – liquid-retaining structures (legacy/UK)
“Values derived from <Standard> (user must verify)” – the tool pre-fills practical rebar densities and typical thickness heuristics but **does not** replace structural design.
Step-by-step: Sample project (complete)
Goal: Underground RCC rectangular sump for an apartment block, target capacity ≈ 40,000 L, internal L:W = 2:1, freeboard 150 mm. Location: Bengaluru (India), units: SI.
- Preset: Click “Underground RCC (Rectangular)”. Set reverse mode = “Given target capacity → find H”, enter 40,000 L, keep L=4.0 m, W=2.0 m, freeboard=0.15 m.
- Thickness (planning): Base 0.25 m, Walls 0.20 m, Top slab 0.15 m (edit per design).
- Rebar densities (IS 3370 profile): Base/Walls 110 kg/m³; Top 90 kg/m³.
- Waterproofing: “External (base+walls)”, overlap 10%.
- Rates (India defaults): Concrete ₹5,600/m³; Steel ₹70/kg; Waterproofing ₹500/m²; Markup 10%.
- Calculate: The tool computes capacity (≈40 kL), concrete volume, rebar weight, waterproofing area, and total cost. Open the HTML report for the printable breakdown.
FAQ
Can I size from litres/gallons? Yes—enable Reverse Mode and enter your target volume.
What about circular tanks? Choose “Cylindrical RCC” and enter diameter as “B”.
Does this cover excavation/backfill? Not directly; use the Earthwork calculator and add to your BOQ.
