It said millionaires were prioritising recycling instead, after a survey of 1,000 high-net worth individuals.
However, they would be better off making changes to their portfolio, which Coutts says would have a bigger impact on the planet.
UK pension funds are worth over £2.7tn, money which Coutts claims could be used to help invest in ethical and sustainable causes.
The bank said its survey revealed how diligent wealthy individuals were about sorting plastic from paper and even flushing their toilets with their bath water.
Over the past five years, 85 per cent of those surveyed had not made changes to their investment portfolio, despite evidence this could be the best way to “green” their lifestyles.
However, 64 per cent had recycled more household items and 60 per cent actively reduced the amount of single-use plastic in their homes.
When it came to food, 40 per cent had bought more ethically or locally produced food while 33 per cent had made energy-efficiency improvements to their homes and 19 per cent had opted for low carbon emission modes of transport.
Leslie Gent, head of responsible investing at Coutts, said: “We know from speaking to our clients that they want to do their best for the planet and are making huge and often time-consuming changes to their lives.
“But what our study reveals is many of Britain’s millionaires do not realise they can make a far bigger difference to the planet with their investments and pensions than they can by sorting their recycling.
“We’re on a mission to educate our clients about the opportunities they have to make a difference through their investment decisions.
“We believe companies that make a positive difference to the environment can also have a positive long-term financial impact on investment portfolios and are keen to ensure our clients make the most of their money as well as knowing the impact it’s having on the planet.
“We’re urging people to have a simple conversation with those who look after their money, starting with their pension provider, about the impacts their investments can and do have.”
How to invest money
Ms Gent said investors should ask themselves the following questions:
- Is my pension fund invested with a “responsible” pension provider?
- If so, what does this mean? For example, how are they selecting companies that have a positive impact on people and the planet? Are there any activities they don’t invest in, such as thermal coal?
- How is the fund manager or pension provider using its influence for good? For example, are they engaging with the companies they invest in to reduce their emissions or have diverse boards?
- How have the green funds they offer against other pension funds, and what do they expect the long-term performance of these funds to be?
- What kind of public commitments have they made as a pension provider/fund manager? For example, have they committed to net zero investments?
- Are they a member of any networks/initiatives such as Climate Action 100+ or the Net Zero Asset Owners Alliance/Net Zero Asset Managers initiative? If so, how are they using these networks to improve their own ESG strategy?
- If I’m not happy with my current fund, what are some responsible or green funds they offer and how can they demonstrate the environmental credentials of these funds?
Research by the Make My Money Matter campaign suggested that making your pension more environmental will save 21 times more carbon than giving up flying, no longer eating meat and switching to sustainable energy – all at once.