Smart Ways to Use Harvested Rainwater at Home

Today’s homeowners are more focused than ever on cutting costs, enhancing sustainability, and adding lasting value to their property.

Rainwater harvesting systems are rapidly emerging as one of the most effective upgrades a modern home can have. Whether you're aiming to future-proof your home, reduce your water bills or your carbon footprint, installing a home rainwater collection system is a practical step with wide-ranging benefits.

Reducing mains water usage is becoming more important in the face of climate change, rising utility prices and growing pressure on the UK’s water infrastructure.

For those planning a self-build or home renovation, underground rainwater harvesting systems can now be incorporated into the property design from the start and are often included in architect plans for new builds.

In new housing developments, particularly in flood-prone areas, rainwater systems are now required under planning regulations in almost all cases since the June 2025 SuDS Standards update.

Even management companies overseeing flats and multi-occupancy buildings are starting to embrace rainwater harvesting to supply water for sprinkler systems or communal outdoor areas, helping to reduce mains water use at scale.

Whether you're focused on cost savings, environmental responsibility, or meeting future regulations, rainwater harvesting is quickly becoming an essential feature of the modern, sustainable home.

Common Uses of Harvesting Rainwater for Homeowners

Let’s explore the practical and versatile ways households are making the most of every drop. Typically, underground tanks are used for collecting water that will be used to in the home, though where space if sufficient, larger above-ground tanks can be used too.

1. Toilet Flushing

One of the most effective ways to utilise harvested rainwater is using it to supply toilets. Toilet flushing is a surprisingly large contributor to domestic water usage.

Why it works:

• Toilets account for up to 30% of the average household’s water use.

• Rainwater is perfectly suited for this purpose, as it doesn’t need to be drinking quality.

• Using non-potable water here saves treated mains water for when it’s truly needed.

How it's done:

Rainwater is collected from rooftops, filtered, and stored in tanks. From there, it’s pumped into a dedicated plumbing system connected to toilet cisterns. Dual-flush systems make the process even more efficient and obviously a mains top-up is essential for when your tanks are empty.

2. Washing Machines

Using rainwater in your washing machine is not only better for the environment but also excellent for your laundry.

Benefits include:

• Softer water: Rainwater is naturally soft, meaning it contains little to no calcium or magnesium. This reduces the need for detergent and helps prevent limescale buildup.

• Less wear on clothing: Softer water is gentler on fabrics.

• Savings on utility bills: Less detergent, less energy spent heating water, and reduced reliance on treated water.

  
  

Modern rainwater harvesting systems can be plumbed directly into your washing machine feed, ensuring a seamless transition from mains to rain. Again, ensuring a mains top-up is available is essential.

3. Garden Watering and Irrigation

This is perhaps the most common and straightforward use for harvested rainwater, and for good reason.

Why it matters:

• Outdoor water use can account for up to 50% of a household’s summer water consumption.

• Mains water often contains chlorine and other additives that plants don't need.

• During hosepipe bans, homes with rainwater tanks can continue watering their gardens legally.

  
  

Applications:

• Watering lawns, flower beds, and vegetable gardens.

• Feeding greenhouse plants.

• Connecting to drip irrigation systems or sprinklers.

  
  

Even a simple water butt connected to your downpipe can make a big difference for the enthusiastic gardener, not only reducing your summer water usage but helping your plants to thrive.

4. Pressure Washers, Cleaning Cars and Outdoor Surfaces

Cleaning your car, patio, or even your windows with rainwater is practical, cost-effective and eco-friendly. It is also ideal for powering pressure washers which typically use a lot of water.

Key advantages:

• Streak-free finish: Because rainwater is soft, it doesn’t leave behind mineral residue or water spots.

• Free from treatment chemicals: Better for car paintwork and garden furniture.

• Reduces pressure on mains supply, particularly in the summer when water demand spikes.

With a hose connected to your rainwater tank (manual or powered), washing down becomes an effortless and guilt-free task.

5. Topping Up Garden Ponds and Water Features

Ponds and fountains often lose water through evaporation and splashing. Using harvested rainwater to top them up is a sustainable alternative to draining your mains supply.

Benefits:

• Better for aquatic life: Tap water can be high in chlorine, which may harm fish and pond organisms. Rainwater is more natural.

• Cost-effective: Large garden features can consume surprising amounts of water over time.

  
  

Ensure your harvested water is filtered to remove debris, especially if you have fish.

6. Household Cleaning (Non-Potable Uses)

Although not suitable for drinking or bathing without proper treatment, rainwater can still be used for general household cleaning tasks.

Uses include:

• Mopping floors

• Cleaning windows and surfaces

• Washing outdoor bins and garden tools

  
  

All these uses reduce the strain on the mains water supply while getting everyday chores done just as effectively.

7. Fire Safety and Emergency Storage (Especially in Flats and Multi-Occupancy Buildings)

While fire sprinkler systems aren’t common in standard houses, they are increasingly required in flats and multi-occupancy residential buildings, especially in new developments or buildings undergoing safety upgrades. In such settings, rainwater harvesting can support fire safety infrastructure.

How this helps:

• In flats, high-rise apartments, and HMOs, rainwater can be stored in tanks that feed sprinkler systems or act as a backup water supply.

• Stored water adds resilience during mains outages or fire emergencies.

• Developers and property management companies may use rainwater harvesting to supply water for fire suppression systems, provided quality standards are met.

  
  

While not typical in single-family homes, this use highlights rainwater harvesting’s role in broader residential safety strategies.

8. Reducing Flood Risk

Perhaps one of the most overlooked benefits of domestic rainwater harvesting is its role in reducing surface water runoff, especially in areas prone to flash flooding.

How it works:

• Instead of water pouring off roofs and overwhelming drainage systems, it’s captured and stored.

• In areas with combined sewers (common in the UK), this prevents overflows and sewage discharge into waterways, helping to keep our rivers and the sea cleaner.

• Some councils actively encourage or require rainwater attenuation systems in new builds as part of flood risk mitigation strategies.

By keeping water out of overburdened storm drains, homeowners contribute to wider community resilience during extreme weather events.

Installation and System Options

There’s a wide range of rainwater harvesting solutions available, from simple DIY water butts to fully integrated underground tanks with automatic pumps and filters.

Common types:

• Water butts/Wall Tanks: Ideal for gardens (including hoses and irrigation) and basic uses outdoors.

• Above-ground tanks: Larger capacity, often used for toilets and washing machines.

• Underground tanks: More discreet, often used in new builds and retrofits with high water demands.

  
  

Some systems come with filtration units that allow for more varied applications. Others can be upgraded with UV treatment if you’re aiming for potable use, though that’s less common in UK homes.

Why Rainwater Harvesting Matters More Than Ever

As climate change reshapes our weather patterns and urban areas become more densely populated, the need for sustainable water management has never been more urgent. In the UK, rainwater harvesting is gaining real traction as a smart, eco-conscious solution for modern homes.

What was once seen as a niche environmental feature is now moving into the mainstream. In fact, some new housing developments are now required to install rainwater harvesting systems as part of planning conditions or building regulations, especially in areas vulnerable to surface water flooding.

The benefits are clear: rainwater harvesting reduces reliance on mains water, lowers household bills, relieves pressure on local drainage infrastructure, and helps mitigate flood risks. By capturing and storing rainfall, these systems prevent runoff from overwhelming sewers and drains, particularly during heavy downpours, which are becoming increasingly common across the UK.

Start Your Rainwater Harvesting Journey Today

Rainwater harvesting is more than just a "green" add-on. It's a practical, cost-saving, and forward-thinking investment in the future of your home. As UK weather becomes less predictable and urban flooding more frequent, capturing rain where it falls isn't just sensible, it’s necessary.

Whether you're flushing loos, growing vegetables, or simply washing your car, every litre of rainwater used is a litre of treated water saved. And with the added benefit of reduced flood risks and lower bills, it’s no wonder this centuries-old practice is making a modern comeback.

Ready to get started? 

Speak to your local rainwater harvesting installer to get the ball rolling, and if you’re based in the South West, we offer a full rainwater harvesting supply and installation service for homeowners, developers and architects, as well as those in the agricultural industry. Drop us a message and we’d be happy to help!