Understanding Water Tank Capacity and How to Choose the Right Size

Understanding Water Tank Capacity and How to Choose the Right Size

Posted on: Nov 26, 2025

The Ultimate Capacity Guide: Choosing the Right Water Tank for Home, Business, and Farm, Water is life. It is the fuel for every home, business, and farm. Without reliable water storage, everything stops. Choosing the correct water tank capacity is a vital choice. It is about security and efficiency.
This is not just for homes anymore. Businesses, offices, schools, and farmers all need proper storage. Guessing the size of your tank is a mistake. You risk shortages or unnecessary costs.
This guide will show you how to calculate the perfect tank size. We will use official standards for three main areas: Domestic, Commercial, and Agricultural. We will also help you choose a strong, reliable tank, like those made by Bansal Poles.

Water Tank Capacity for the Home (Domestic Use)

Your home needs a constant supply of safe drinking water. We rely on official standards to calculate the necessary residential water storage.

The Official Domestic Standard: 135 LPCD

The Bureau of Indian Standards (BIS) provides a clear figure. This is found in the BIS Code IS 1172: 1993. It states the standard for domestic water consumption in cities is 135 liters per capita per day (LPCD). This applies where you have a proper flushing system.

This 135 liters per person covers all essential needs:

Daily Activity	Standard Water Use (LPCD)
Drinking, Cooking, Bathing	70 liters
Toilet Flushing	30 liters
Clothes and House Washing	35 liters
Total Domestic Use	135 Liters

The Home Capacity Formula

To find your home's required water tank capacity, use this simple formula. We recommend a minimum of 2 days of backup supply.
Required\ Capacity (in Liters) = (Number of People) x (135 LPCD) x (Number of Days of Storage)
Example: A family of 5 needs 2 days of backup.
⦿ 5 People x 135 Liters x 2 Days = 1350 Liters
⦿ Recommendation: Two 750-liter tanks, or two 1000-liter tanks for a larger safety margin. Always round up your final number.
This simple math using the official water consumption per person figure ensures you select the correct overhead water tank size.

Water Tank Capacity for Business (Commercial Use)

Commercial buildings have very different water needs than homes. The calculation depends on the function of the building. This is called commercial water storage capacity.

Different Commercial Needs

Commercial calculations also use LPCD, but the required amount varies widely:
⦿ Offices/Shops: People spend only part of the day here. The need is lower. You may only need 45 to 60 LPCD.
⦿ Restaurants: Water is needed for cooking, cleaning, and customer use. Needs are higher. Around 135 to 150 LPCD per seat is often used.
⦿ Hotels: These run 24/7. They need high volumes for washing, guests, and laundry. Needs can be 180 to 225 LPCD per bed.
⦿ Schools: Needs are high during the day. Around 45 to 90 LPCD per student/staff member.

The Commercial Capacity Formula

You must first determine the right LPCD for your building type. Then, multiply it by the number of people served (employees, students, or guests).
Commercial Capacity (L) = (Total Occupants) x (Commercial LPCD) x (Days of Storage)
Example: A small office with 50 employees and a need for 2 days of backup (using 60 LPCD).
⦿ 50 Employees x 60 Liters x 2 Days = 6000 Liters
⦿ Recommendation: Six 1000-liter tanks or larger underground tanks.
For commercial water storage capacity, flexibility is key. Using several 1000-liter tanks is often easier for installation and maintenance than using one huge tank.

Water Tank Capacity for Farming (Agricultural Use)

Water storage for farming is the most complex. It is not calculated by people. It is calculated by land area, crop, or livestock. This is known as agricultural water needs.

Two Main Agricultural Needs

1. Irrigation: This is the water needed to grow crops. Needs are measured in terms of millimeters of water per day over the land area. This changes constantly based on weather and crop type.
? Simple Estimate: A general rule is that one acre of land may need around 20,000 to 30,000 liters of water per day during the peak growing season.
2. Livestock: Animals need daily drinking water.
   ⦿ Cattle: 45-60 liters per cow per day.
   ⦿ Poultry: 0.2 to 0.5 liters per bird per day.

The Agricultural Capacity Formula

You must calculate based on your largest need (usually irrigation).
Agricultural Capacity (L) = (Liters needed per day for all uses) x (Number of Days of Storage)
Example: A farm that needs 40,000 liters per day for irrigation and livestock, with a 3-day backup goal.
⦿ 40,000 Liters $\times$ 3 Days = 120,000 Liters (1.2 Lakh Liters)
⦿ Recommendation: Large-scale storage is needed, often using underground or heavy-duty modular tanks.
For large agricultural water needs, a combination of small, modular storage and large ground-level tanks is common.

Choosing Quality and Safety: ISI Certification for All

Once you know the capacity, you must select a quality tank. This is true for a home, a factory, or a farm. Water must remain clean and safe.
The best guarantee of quality is the ISI mark. This certification means the tank meets the tough standards set by the Bureau of Indian Standards (BIS).
For plastic tanks, the standard is IS 12701. An ISI certified water tank guarantees several things:
1. Purity: It is made from 100% virgin and food-grade plastic. This is essential, even for agriculture, to prevent chemical leaching.
2. Durability: The tank is tested for strength and structural integrity.
3. UV Protection: The tank is UV protected. This is vital when the tank is sitting outside in the sun all day.

Bansal Poles: The Flexible Solution for Every Need

Bansal Poles water tanks are built to serve all three sectors: residential, commercial, and agricultural. Their focus on quality and modularity makes them flexible.
While their standard capacities are 500 liters, 750 liters, and 1000 liters, their strength lies in using these units to build large systems.
Key Features for All Applications:
⦿ Unmatched Purity: Every tank uses 100% virgin and food-grade materials. This ensures the water is safe, whether for drinking, cooking, or crop irrigation.
⦿ Anti-Microbial Properties: Added safety for your family's health
⦿ Built for Outdoors: The tanks are 100% UV protected water tank material. They resist sun damage and maintain their strength for many years.
⦿ Superior Strength: The unique six-shoulder design and Multi-Ribbed Design make the tanks robust. They can handle the full water weight without failing. This is especially important when tanks are installed on elevated commercial roofs or farm structures.
⦿ Modular Advantage: For large commercial water storage capacity or agricultural water needs, you can link multiple Bansal Poles 1000-liter units. This system is easier to maintain. If one tank needs cleaning, the others remain operational.
Bansal Poles offers a 10-Year Warranty on their tanks. This guarantee shows their confidence in their product's lasting performance in all applications.

Securing Your Water Future

Whether you are calculating Water Tank Capacity for a small home using the 135 LPCD rule, a bustling office, or a large farm, the principle is the same: Calculate Accurately and Buy Quality.
Use the official standards to determine your exact capacity need. Then, choose a durable, ISI certified water tank from a brand you can trust. By selecting a high-quality, UV protected water tank like the Bansal Poles range, you secure a reliable water future for your operations, big or small.