What Size Bunded Oil Tank Do I Need? A Complete UK Buyer’s Guide

Choosing the correct bunded oil tank size is one of the most important decisions for homeowners and businesses that rely on heating oil. The right tank capacity affects fuel efficiency, delivery costs, storage safety, and long-term convenience. Select a tank that’s too small and you’ll face frequent refills; choose one that’s too large and you could waste money and valuable space.

In this guide, we explain how to choose the right size bunded oil tank by looking at annual oil usage, property type, available space, and refill frequency. Whether you’re replacing an old tank or installing a new one, this guide will help you make an informed, cost-effective decision.

What Is a Bunded Oil Tank?

A bunded oil tank features a double-skinned design: an inner tank that stores oil and an outer tank (the “bund”) that acts as secondary containment. This design helps prevent leaks and protects the environment, making bunded tanks the recommended and often required choice for both domestic and commercial properties across the UK.

You can explore a full range of compliant options in the Oil Tanks Plus bunded oil tanks collection.

How to Choose the Right Bunded Oil Tank Size

1. Domestic vs Commercial Oil Usage

Your tank size should match how much heating oil you realistically use each year.

Typical UK usage estimates:

  • Small homes: ~1,000 litres per year

  • Average homes: 1,200–1,500 litres

  • Large homes: 2,000 litres+

  • Commercial premises: 2,500–5,000+ litres

The number of occupants, insulation levels, boiler efficiency, and heating patterns all influence consumption. This guide from Certas Energy explains heating oil tank sizes and household demand in detail.

2. Understanding Annual Oil Consumption

Knowing your annual oil usage is the most accurate way to choose the right tank size. If you’ve lived in the property for a few years, check delivery records. If not, estimate based on:

  • Property size

  • Number of people living in the home

  • Heating system efficiency

  • Whether oil is used for hot water as well

BoilerJuice offers helpful insights into how household size affects heating oil tank capacity.

3. Space & Installation Considerations

Bunded oil tanks are available in multiple shapes and footprints, but space constraints often determine the maximum size you can install.

Before choosing a tank:

  • Measure the installation area carefully

  • Allow access for maintenance and inspections

  • Consider delivery access for tanker hoses

  • Check local regulations and OFTEC separation distances

Slimline or low-profile bunded tanks are often ideal for tight spaces.

4. How Often Do You Want to Refill?

Tank size directly affects refill frequency:

  • Smaller tanks = lower upfront cost, more frequent deliveries

  • Larger tanks = fewer deliveries, better bulk-buy pricing

Many homeowners prefer a tank that holds at least 12 months of oil, reducing winter delivery risks and allowing them to buy oil when prices are lower.

Should You Upsize or Downsize Your Oil Tank?

When Upsizing Makes Sense

  • You want fewer deliveries per year

  • You plan to buy oil in bulk

  • Your household or business may expand

  • You’re replacing an older, undersized tank

When Downsizing Is Better

  • Limited installation space

  • Lower oil usage than previous occupants

  • Budget constraints

  • Transitioning to more efficient heating systems

The key is choosing a tank that matches current needs with some future flexibility.

Common Bunded Oil Tank Sizes (Quick Reference)

Tank Size Best For
1,000 litres Small homes
1,500 litres Average households
2,000 litres Large homes / small businesses
2,500–5,000 litres Commercial properties

To explore all available options, browse the full range at Oil Tanks Plus.

Final Thoughts: Choosing the Right Oil Tank Size

Selecting the correct bunded oil tank size helps you save money, reduce inconvenience, and ensure safe, compliant oil storage. By understanding your annual oil usage, space limitations, and refill preferences, you can confidently choose a tank that suits your property and lifestyle.

For assistance in selecting the perfect oil tank, or to get a custom quote, don’t hesitate to contact us today!