Wall Tanks vs Underground Rainwater Systems: What’s Best for Your Home?

Rainwater harvesting is becoming an increasingly popular way for homeowners to reduce water bills, improve garden health and prepare for future water restrictions. But one of the most common questions we hear is:

Should I choose a wall tank or an underground rainwater harvesting system?

The answer depends on your space, budget, and how you plan to use the water. This guide breaks down the key differences to help you choose the right rainwater harvesting system for your home.

What Is a Wall Tank Rainwater System?

Wall tanks (also known as above-ground rainwater tanks) are connected directly to your downpipe and store rainwater externally, usually against an outside wall.

Benefits of Wall Tanks

• Easy and quick to install
• Lower upfront cost
• Ideal for gardens and outdoor use
• No excavation required
• Available in decorative designs

Wall tanks are perfect for homeowners looking to collect rainwater for watering gardens, washing cars, or general outdoor cleaning.

Things to Consider

• Limited storage capacity compared to underground systems
• Visible installation (although modern designs are very discreet)
• Best suited to outdoor use only

What Is an Underground Rainwater Harvesting System?

Underground systems collect and store rainwater below ground in a tank, supplying water directly to appliances or irrigation systems.

Benefits of Underground Systems

• Large storage capacity
• Hidden from view
• Can supply water for:
  • Toilet flushing
  • Washing machines
  • Irrigation systems
• Ideal for long-term water savings

These systems are often chosen for new builds or major renovations, but can also be retrofitted to existing homes.

Things to Consider

• Higher installation cost
• Requires groundworks
• Longer installation time

Which Rainwater Harvesting System Is Right for You?

Choose a wall tank if you:

• Want a simple, cost-effective solution
• Mainly use water outdoors
• Have limited space or budget

Choose an underground system if you:

• Want maximum water savings
• Plan to use rainwater indoors
• Are building or renovating
• Want a discreet, long-term solution

Another option could be to combine both an under and above ground system. This option could maximise your water storage.

All of these options significantly reduce reliance on mains water and help future-proof your home against rising water costs.

Final Thoughts

Whether you choose a wall tank or an underground system, rainwater harvesting is a smart investment for your home and garden. The right system depends on how you live, how much water you use, and how much space you have available.

If you’re unsure which option suits your property, our team can help you choose a system that fits your needs now and in the future. You can reach a member of the team by filling out our contact form or alternatively you can give us a call on 01733 405 111.