Rainwater harvesting tanks are an essential part of any effective water-saving system. They allow you to collect and store rainwater for various uses — from gardening and irrigation to flushing toilets and cleaning equipment. Choosing the right tank size is crucial to ensure your system meets your needs and operates efficiently. This guide will help you determine the ideal tank for your property.
Why Choose Rainwater Harvesting Tanks?
Rainwater harvesting tanks offer an eco-friendly way to save water and reduce utility bills. These systems collect rainwater, store it safely, and allow you to use it for non-potable — and, with proper filtration, even potable — purposes. Whether for domestic or commercial use, rainwater harvesting tanks are a practical way to conserve resources and reduce costs.
Explore our full range of rainwater harvesting tanks to find the perfect option for your property.
Factors to Consider When Choosing the Right Tank Size
1. Daily Water Usage
Understanding your water requirements is the first step. For instance:
- Small households may require tanks with capacities up to 1,500 litres.
- Farms or commercial setups — such as irrigation systems — may need larger tanks ranging from 10,000 litres to 30,000 litres or more.
Browse our range of high-capacity tanks from trusted brands such as Enduramaxx and GRAF.
2. Roof Catchment Area
The size of your roof directly affects how much rainwater you can collect. For example, a 50m² roof in a region with 800mm annual rainfall can collect approximately 40,000 litres per year. Knowing this helps you select a tank that aligns with your collection potential.
3. Rainfall Patterns in Your Area
Regions with consistent rainfall can rely on smaller tanks due to regular replenishment. However, areas with irregular rainfall benefit from larger tanks to store water for dry periods.
4. Purpose of Use
The right tank size depends on your intended use:
- Domestic use: Tanks under 1,500 litres are ideal for garden irrigation, washing cars, or flushing toilets.
- Commercial or agricultural use: Larger tanks, such as those by Enduramaxx, are perfect for irrigation, machinery washing, or watering livestock.
Types of Rainwater Harvesting Tanks
1. Above-Ground Rainwater Harvesting Tanks
Easy to install, maintain, and relocate if required, these tanks are ideal for homes and small businesses. Explore our range of above-ground tanks to find a suitable solution for your property.
2. Below-Ground Rainwater Harvesting Tanks
Designed for larger storage needs, below-ground tanks save space and keep water cooler, reducing bacterial growth. These are ideal for farms, commercial properties, and sites with higher water demands. Learn more about our below-ground tanks.
How to Calculate the Right Tank Size
- Calculate water demand: Estimate daily or monthly water use based on your activities.
- Measure roof catchment area: Use your roof dimensions and local rainfall data to calculate water potential.
- Consider rainfall frequency: Smaller tanks suit wet regions; larger ones suit dry climates.
- Choose the right brand: Whether you need a compact GRAF tank or a high-capacity Enduramaxx system, Cotterill Civils has a solution for every application.
If you’re unsure which tank suits your property, our team of experts is happy to help.
FAQs About Rainwater Harvesting Tanks
How do I calculate the right tank size?
Consider your water usage, roof area, and local rainfall. For most households, a 5,000-litre tank works well, while farms or commercial setups may require significantly larger capacities.
What’s the difference between above-ground and below-ground tanks?
Above-ground tanks are easier to install and maintain, while below-ground tanks save space, protect water from temperature changes, and offer larger storage volumes.
Are rainwater harvesting tanks worth it in the UK?
Yes — the UK’s regular rainfall makes these systems a highly cost-effective and sustainable investment for both homes and businesses.
Why Choose Cotterill Civils?
At Cotterill Civils, we’ve helped thousands of customers across the UK find the ideal rainwater harvesting tank for their property. Whether you need an above-ground system for a small garden or a high-capacity below-ground tank for a farm, we have the expertise and product range to help.
We stock tanks from leading brands like Enduramaxx and GRAF, and our friendly team can advise you on capacity, placement, and system setup.
For more information or a free consultation, visit our enquiry page or call us today on 0121 351 3230.
