How to Choose the Right Rainwater Tank for Your Home or Business

Rainwater harvesting is becoming increasingly popular in the UK as more people look for ways to reduce water bills, conserve resources, and become more self-sufficient. One of the most important decisions when setting up a rainwater harvesting system is choosing the right plastic water storage tank. With so many options available, it can be overwhelming to determine which tank best suits your needs.

This guide will take you through the key factors to consider when selecting a plastic rainwater tank, including tank size, installation type, and maintenance requirements. Whether you need a small water butt for your garden or a large plastic underground storage tank for a business, this article will help you make an informed choice.

1. Determine Your Water Usage Needs

Before choosing a rainwater tank, it is essential to estimate how much water you will need. Consider the main uses of harvested rainwater, such as:

• Garden irrigation – Watering plants, lawns, and vegetable gardens.
• Domestic use – Flushing toilets, washing clothes, and cleaning.
• Commercial or agricultural use – Irrigation for crops, livestock watering, or industrial processes.

The amount of water you can collect depends on your roof size and average rainfall in your area. As a general rule, a roof can collect about 1,000 litres of water for every 1mm of rain per 100m² of roof area. If you plan to use rainwater for multiple purposes, opting for a larger tank will ensure you have enough supply, especially during dry periods.

2. Choosing the Right Tank Size

Once you have estimated your water usage, you need to decide on the tank capacity. Here are some common sizes and their typical applications:

• 200 – 500 litres – Suitable for small gardens or occasional outdoor use.
• 1,000 – 2,500 litres – Ideal for larger gardens, washing cars, or supplementing domestic use.
• 5,000 – 10,000 litres – Suitable for households using rainwater for toilets, washing machines, and general household tasks.
• 10,000+ litres – Best for large properties, farms, or commercial buildings requiring significant water storage.

If space is limited, you may consider linking multiple smaller tanks together to increase storage capacity while maintaining flexibility in placement.

3. Why Choose a Plastic Rainwater Tank?

Plastic water tanks are the most popular choice for rainwater storage due to their durability, affordability, and ease of installation. Here are the key benefits of plastic rainwater tanks:

• Lightweight and easy to install – Unlike metal or concrete tanks, plastic tanks are easier to transport and set up, reducing installation costs.
• Corrosion-resistant – Plastic does not rust, making it ideal for long-term water storage.
• UV-resistant – High-quality plastic tanks are designed to withstand sun exposure, preventing algae growth.
• Available in a variety of sizes and shapes – Whether you need a slimline tank for a tight space or a large underground storage solution, plastic tanks provide flexibility.

4. Above-Ground vs. Underground Plastic Tanks

The location of your tank will depend on available space, budget, and water usage requirements.

Above-Ground Plastic Tanks

• Easier to install and maintain.
• More affordable and accessible for inspections.
• Require a shaded area to reduce algae growth.

Underground Plastic Tanks

• Space-saving and hidden from view.
• Keeps water cool and reduces evaporation.
• More expensive to install due to excavation costs.
• Requires a pump for water distribution.

For homes with limited outdoor space, underground plastic tanks offer an excellent solution, while above-ground plastic tanks are a more cost-effective choice for easy access and maintenance.

5. Installation Considerations

Before purchasing a tank, consider the installation requirements, including:

• Base preparation – Tanks must be placed on a stable, level surface such as a concrete slab or compacted sand.
• Gutter and downpipe connections – Ensure your roof’s drainage system efficiently channels rainwater into the tank.
• Filtration systems – Install first-flush diverters and filters to prevent debris from entering the tank.
• Pumps and plumbing – If using rainwater for indoor applications, you may need a pump and connection to existing plumbing.

6. Maintenance Requirements

To ensure your rainwater harvesting system functions efficiently, regular maintenance is essential. This includes:

• Cleaning gutters and downpipes to prevent blockages.
• Checking and cleaning filters and first-flush diverters.
• Inspecting the tank for leaks or structural issues.
• Treating water if required, particularly for indoor use.

Plastic water tanks typically require minimal maintenance, making them a hassle-free option for homeowners and businesses.

7. Choosing the Right Rainwater Harvesting Kit

For those looking for a complete solution, a rainwater harvesting kit can simplify the process. These kits usually include:

• Plastic storage tanks in various sizes.
• Gutter filters and diverters.
• Pumps for water distribution.
• Plumbing components for easy integration.

Investing in a kit ensures all components are compatible and designed to work efficiently together, making installation quicker and more straightforward.

Final Thoughts

Choosing the right plastic rainwater tank depends on several factors, including your water usage, available space, budget, and installation preferences. By carefully considering the size, type, and placement of your plastic water tank, you can ensure a reliable and long-lasting water storage solution.

At Water Tank Supplies, we offer a wide selection of plastic rainwater harvesting tanks and complete rainwater harvesting kits to suit every home and business. Explore our range today and start making the most of your rainwater collection system!