Water Tank Capacity Calculator

Calculate Your Water Tank Capacity in Liters

Whether you are digging an RCC (Reinforced Cement Concrete) sump under your parking lot or buying an overhead plastic tank (often popularly referred to in India as a "Sintex" or "Syntax" tank), knowing the exact water tank capacity in liters is essential for managing your home's daily water supply.

Indian Water Consumption Thumb Rules

According to the BIS (Bureau of Indian Standards), standard domestic water consumption is estimated at 135 Liters per capita per day (lpcd). For a standard family of four, this means you need approximately 540 liters of water daily for drinking, cooking, bathing, and flushing.

The Science of Water Conversion

To find the capacity of a tank, we first find its internal volume in standard units like Cubic Feet (CFT) or Cubic Meters (m³), and then convert that volume into Liters.

Rule 1: 1 Cubic Meter (m³) of volume holds exactly 1,000 Liters of water.
Rule 2: 1 Cubic Foot (CFT) of volume holds exactly 28.31 Liters of water.

Using the Underground Water Tank Size Calculator

Underground water tanks (sumps/haud) are typically rectangular. Let's look at how to calculate the capacity step-by-step.

Rectangular Tank Formula

Volume = Length × Width × Depth

Example Calculation (Measured in Feet):
Let's say your underground RCC tank is 6 ft long, 4 ft wide, and 5 ft deep.
Step 1: Calculate Volume = 6 × 4 × 5 = 120 CFT.
Step 2: Convert to Liters = 120 CFT × 28.3168 = 3,398 Liters.

Cylindrical Tank Formula (Overhead / Sintex Type)

Overhead plastic tanks are mostly cylindrical. To find the volume, you need the internal diameter and the height of the water level.

Volume = π × r² × Height
(Where π is approx 3.1415, and r is the radius, which is half of the diameter).

Example Calculation (Measured in Meters):
Let's say your cylindrical tank has a diameter of 1 meter and a height of 1.5 meters.
Step 1: Find Radius = 1 meter ÷ 2 = 0.5 meters.
Step 2: Calculate Volume = 3.1415 × (0.5 × 0.5) × 1.5 = 1.178 m³.
Step 3: Convert to Liters = 1.178 m³ × 1000 = 1,178 Liters.

Important Contractor Tip: Always measure the internal dimensions of the tank! Wall thickness (like a 9-inch brick wall) takes up a lot of space and will heavily reduce your actual water tank capacity in liters if you mistakenly use the outside measurements.