THE HORROR OF WATER WASTE! | Rainwater Harvesting guide

Original blog posted in April 2022

Back in 2019, I was asked to put together a panel discussion for The Landscape Show on rainwater harvesting systems. Straightforward enough, I thought.

What started as event preparation quickly became a deep dive into the UK's relationship with water, and some of the figures were staggering. 

According to the Consumer Council for Water, England and Wales lose more than 3 billion litres of water every single day through leaking pipes alone. That's enough to fill around 1,180 Olympic swimming pools, every single day! At the same time, the average person in the UK now uses more than 140 litres of water daily, and that number continues to rise. * 

The picture becomes pretty obvious: The UK has a water problem! 

Replacing ageing infrastructure isn't something most of us can influence. But there's something our industry can do right now. 

Stop letting useable rainwater disappear down the drain. 

At Landscapeplus, we've been specifying and supplying irrigation systems to landscapers, irrigation installers and contractors across the UK for over 25 years. We are determined to help the industry make a positive impact, so let's look at how rainwater harvesting systems can shape the future. 

The industry opportunity for rainwater harvesting

With Sustainable Drainage Systems (SuDS) regulations increasingly shaping development design, the direction of travel is becoming clear. Rainwater harvesting is gradually moving from "nice-to-have" to "preferred" within the world of garden irrigation. 

Why do so many landscapers avoid it?

Usually, it comes down to one thing: the unknown. Mention a "tank-based irrigation system" and many people immediately assume complexity, cost and awkward client conversations. 

But strip away all the terminology and garden irrigation systems are actually very simple. Whether it's a watering can or a fully automated setup, every system needs just four things: 

• A water source: tap, water butt, or a water tank (above our below ground)
• A trigger: manual control, a timer, or a smart controller
• A way to move water: pipework, hoses or even a watering can
• A delivery method: driplines, sprinklers or spray heads

That's really all it is.

Sure, it's a step up from a watering can or hosepipe, but once your rainwater harvesting systems are up and running, your client will be set for years to come. 

Why specify a rainwater harvesting system? 

Using harvested rainwater instead of relying purely on the mains for garden irrigation brings several advantages:

• Lower running costs: Rainwater is free, which can create meaningful savings over the lifetime of a system
• Healthier plants: Rainwater is naturally softer and better suited to many plant species than treated mains water
  • Check out this article on how good rainwater is for your plants >>

• Less dependence on restrictions: During dry periods or hosepipe bans, stored rainwater can keep systems running 
  • Dealing with a hosepipe ban >>

• Better environmental credentials: Clients increasingly want sustainability built into projects rather than added as an afterthought 
• Smarter watering: Automated systems deliver water precisely where it's needed, reducing both waste and guesswork

How to specify rainwater harvesting systems 

You don't need to be an irrigation expert to specify one of these systems. Follow these steps and you'll be good to go. 

1. Work out how much roof area can collect - Every 1m² of roof collects roughly 0.9 litres of usable water per millimetre of rainfall. 
2. Size your tank correctly to suit - Work out the irrigation demand of the system. How much water is needed per week in peak season. Your tank should hold two to four week' worth. 
3. Plan pipework early in the design process
4. Choose a suitable irrigation controller
5. Match irrigation methods to planting zones 

Most importantly: think about it at the start of a project, not as retrofit later. 

The future of garden irrigation in the UK

The industry is already moving in one direction. 

Rainwater harvesting isn't likely to remain a specialist feature for much longer. The designers and contractors who understand it now will be ahead of the curve. 

Think you're ready?

If you need helping specifying or just want to know more, get in touch with the team here >>

*Stats still accurate for 2026