When building a home or commercial building, one of the most important parts of your plumbing system is the overhead water tank (OHT). It makes sure your house gets a steady water supply throughout the day. But a common question most people have is: “How big should my water tank be?” That’s where this Overhead Tank (OHT) Capacity Calculation Guide comes in handy.
In this blog, we’ll explain everything you need to know about calculating the right size for your overhead tank — in simple, everyday language. Whether you’re constructing a new home, renovating an old one, or just curious about your current tank size, this guide will help you understand the basics without complicated jargon.
At Rightcon Constructions, we specialize in delivering high-quality, affordable homes designed to fit your vision. Whether you’re building from scratch or expanding your space, we bring your ideas to life with experts, timely delivery, and a commitment to excellence. Our experienced team ensures a smooth, hassle-free construction process, tailored to your budget and style. Get Free Cost Estimation. Contact Us: 96065 92959 Visit Now: https://rightcon.in/
What Is an Overhead Tank (OHT)?
An overhead tank (OHT) is a water storage container placed at a certain height above the ground, usually on the rooftop or a high platform. The main job of an OHT is to store water and use gravity to distribute it to taps, showers, flushes, and other fixtures in your building.
Why is it placed overhead?
Because when water is stored at a height, it creates pressure naturally, allowing water to flow downwards to different points without the need for a motor or extra pumps.
Why Is It Important to Calculate OHT Capacity?
Choosing the right size for your overhead water tank is very important. If it’s too small, you’ll keep running out of water. If it’s too big, you’ll waste money on an oversized tank you don’t really need. Also, too much stored water can get stale and unhygienic.
The benefits of proper OHT capacity calculation:
*Ensures 24/7 water availability
*Saves on construction costs
*Prevents water wastage
*Maintains hygiene by storing just enough water
*Avoids unnecessary roof load
Factors to Consider Before Calculating OHT Capacity
Before you jump into calculations, there are a few things you need to know about your home or building:
1️⃣ Number of People in the House
More people = More water consumption.
2️⃣ Daily Water Usage Per Person
On average, an individual uses 135 to 150 liters per day in India for daily needs like drinking, cooking, bathing, washing clothes, and cleaning.
3️⃣ Purpose of Water Usage
Is the water for domestic use only or also for gardening, vehicle washing, or other needs? You’ll need to add extra capacity for these.
4️⃣ Number of Bathrooms and Taps
More water outlets = more water requirement.
5️⃣ Number of Storage Days
Do you want to store water for 1 day, 2 days, or more? Depending on the water supply frequency in your area, this may vary.
6️⃣ Tank Placement Area and Load Capacity
The rooftop or structure should be able to safely hold the weight of the full tank
Basic Formula for OHT Capacity Calculation
Total OHT Capacity (in liters)=Number of People × Daily Water Requirement per Person (in liters)×Number of Storage Days
Example Calculation for a House
Let’s make this clearer with a real-world example.
Example:
Number of family members: 5
Daily water requirement per person: 135 liters
Number of storage days: 1
Calculation:
5×135×1=675 liters
So, you need an overhead tank of 675 liters capacity.
It’s generally advisable to round it off to the next available standard tank size in the market, like 750 liters or 1000 liters.
Note:
If your area has irregular water supply and you need backup for 2 days, then:
5×135×2=1350 liters
In this case, a 1500-liter tank would be suitable.
Standard Overhead Tank Sizes in India
Overhead tanks are available in various standard sizes in India. Here are a few popular ones:
*500 liters
*750 liters
*1000 liters
*1500 liters
*2000 liters
*5000 liters (for larger buildings)
Different Types of Overhead Water Tanks
When choosing your tank, it’s not just about the size. The type of material also matters for durability, hygiene, and cost.
Types of tanks commonly used:
Plastic (PVC) tanks – lightweight, easy to install, affordable
Concrete tanks – heavy-duty, long-lasting, but expensive
Stainless steel tanks – hygienic, rust-free, but costly
FRP (Fiber Reinforced Plastic) tanks – strong and corrosion-resistant
Tips for Choosing the Right Overhead Tank
✅ Always go for food-grade plastic or rust-proof material
✅ Choose a reputed brand with an ISI mark for quality assurance
✅ Make sure the lid fits tightly to prevent dirt and insects
✅ Check if the area where you plan to install can handle the weight
✅ Always provide a proper overflow and vent system
Frequently Asked Questions (FAQs)
Q1. Can I install multiple small tanks instead of one big one?
Yes, especially in apartments or buildings with multiple units. It helps divide water supply evenly and reduces the risk of water shortage.
Q2. How often should I clean my overhead tank?
At least once every 6 months to avoid dirt, algae, and contamination.
Q3. How do I know if my existing OHT is sufficient?
Track your daily water consumption and check how quickly your tank empties. If you frequently run out of water, it’s a sign you need a larger capacity.
Q4. Is it better to have a concrete or plastic OHT?
Plastic tanks are more popular for homes because they’re affordable, lightweight, and easy to maintain. Concrete tanks are better for larger buildings due to their strength.
Read Our Related Articles
✅ Construction Process of Residential Building 2024 in India
✅ Which Brick is Best for House Construction?
✅ Best Construction Company In Bangalore & Mysore
✅ Site Preparation: Why Is It Important for Construction?
✅ Best Soil Testing Method for Construction
✅ Which Grade of Concrete is Used for Slab?
✅ Best Building Contractors Near Me | Bangalore
✅ What are The Materials Required for the Construction of a House?
✅ How To Calculate Construction Cost Per Square Feet in India 2024
✅ Duplex House Construction Cost in Bangalore
✅ What is Construction Management? An Essential Guide
✅ What are The Different Types of Flooring Materials?
Conclusion
Choosing the right size for your overhead water tank is an important decision for any home. It makes sure your family has enough water every day for drinking, cooking, bathing, and cleaning. If the tank is too small, you might run out of water when you need it the most. If it’s too big, you’ll end up wasting money and water. That’s why it’s smart to calculate your water needs properly using a simple method like the one we explained in this Overhead Tank (OHT) Capacity Calculation Guide.
At the end of the day, it’s better to plan ahead than deal with water problems later. Pick a good quality tank, install it safely, and clean it every few months to keep the water clean and healthy. If you’re confused about the size, use an online calculator or ask a plumber for advice. With a little planning, you can enjoy a steady water supply at home without any worries.
