Rainwater harvesting

Although the Isle of Man Biosphere tends to have a lot of rainfall we are experiencing more frequent drier periods and our demand for water is increasing.   

If you are lucky enough to have a garden or outdoor plants then you can prepare for the drier months by harvesting rainwater and installing a water butt.     

What is a water butt? 

A water butt is a container that is used to collect and store rainwater. When it rains, the water is caught in a drainpipe and flows into the water butt. This water can then be used in the garden to water plants and top up ponds during drier periods.  

Why get a water butt? 

Tap water is treated with chemicals such as chlorine to make it safe for human consumption. Rainwater contains nitrates and other organic matter that feeds plants and is slightly acidic which is what the majority of plants prefer.  

Water butts are a handy way of storing rain water for use in the garden whenever you need it, without having to use your mains supply. By storing and using rainwater and not your mains supply you could save 24,000 litres of tap water a year. 

A significant amount of energy and treatment are used to provide safe water to our homes for consumption. Using stored rainwater in your garden will conserve the treated water for its main purpose and lowers carbon emissions.  

Top tips for water butts 

• Find a suitable space for your water butt. You will need a flat, firm surface next to a gutter downpipe.  
• Raise your water butt off the ground so you can use the tap and fit a watering can underneath. If the water butt does not come with a stand, use bricks, and stack them up to make a stable, solid base. 
• Water butts are available in different sizes so make sure you buy the right size butt for the available space. 
• look out for a shady space to help keep the water temperature down and reduce legionella risk.  
• Insulate the water butt with a reflective material to reduce the water temperature rising in warm weather.  
• Keep a lid on the water butt so that insects and debris can’t get in. 
• As well as watering your garden, your water butt can also be used to top up ponds, which is far better for wildlife than tap water. 
• Use a watering can rather than attaching a hose to the water butt.   
• You don’t need to buy a water butt, any container will do.  Leave it out to collect rainwater, cover in the drier periods and dip a watering-can in when needed.    

Be aware of Legionella 

Legionella thrives in warm stagnant water, above 20℃, making water butts the perfect breeding ground. The best way to prevent legionella is to keep water below 20℃ and if possible, place the water butt in a shaded spot or use a reflective cover around the water butt to keep the heat out.   

If water contaminated with legionella is sprayed, it can be very easily inhaled. As a precaution, avoid using a hose or sprinkler. Using a watering-can will reduce the chances of inhaling the bacteria.   

How to fit a water butt 

There are two ways to fit a water butt. The easiest way is to cut through the plastic down pipe and place the butt directly underneath it. An overflow pipe can be attached to the butt to channel away excess water to a drain or to another butt. 

Alternatively, cut a notch out of the pipe and fit a rain trap and connecting pipe, this will transport water to the butt and allows you to place it in the most suitable place.

For more useful ideas on saving water check out our handy leaflet.