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Water Tank Capacity Calculator

Calculate the storage volume, water depth, and supply duration for rectangular and circular water tanks.

Project Specifications
Tank Geometry
Supply Estimation
Standard LPCD = 135-150
Volume conversion
Cubic Meters: 0 m³
US Gallons: 0 gal
Supply Duration: 0 Days
Calculated Output
Total Capacity
0 Liters
0 L
Liters
0 Tons
Water Weight
Comprehensive Guide

Hydro-Volumes and Sanitary Engineering

Learn the volumetric constants of water, the standard daily requirements for households, and the structural implications of water weight.

The Fundamental Constant

Calculating water capacity is the foundation of plumbing and sanitary engineering. The most critical number to remember is that $1.0$ Cubic Meter ($1$ m³) of space holds exactly $1000$ Liters of water. This relationship allows us to easily convert geometric measurements into fluid volumes.

Volume Formulas

$$\text{Rectangular: } V = L \times W \times H \times 1000$$ $$\text{Circular: } V = \pi \times \left(\frac{D}{2}\right)^2 \times H \times 1000$$

Standard Daily Water Consumption

Engineers design tanks based on **LPCD** (Liters Per Capita per Day).

  • Standard Residential: $135$ L to $150$ L per person.
  • Office / Commercial: $45$ L per person.
  • Hospitals: $340$ L to $450$ L per bed.
To ensure continuous supply during maintenance or power outages, a domestic tank is usually sized for $1$ to $2$ days of total household consumption.

Structural Weight Considerations

A common mistake is underestimating how heavy water is. Water has a density of $1000$ kg/m³ ($1$ Tonne per m³). A $5000$-liter tank adds a static load of **5 Metric Tons** (plus the weight of the concrete tank) to the roof slab. This concentrated load must be specifically accounted for by the structural engineer, often requiring additional beams under the tank location.

Frequently Asked Questions (FAQ)

What is 'Freeboard'?

A water tank should never be filled to the absolute brim. Freeboard is the air space (usually $150$mm to $300$mm) left between the top of the water and the tank's ceiling. This space is necessary for the float valve to function and to prevent sloshing or overflow due to air pressure.