Washing your hands with soap reduces your risk of illness. Picture: Lulama Zenzile

If you want to make sure you have washed your hands properly, perhaps you could try bursting into tune.

For ensuring you have removed all the germs should require 20 seconds at the sink – long enough to sing Happy Birthday twice – experts say.

Failing to kill bacteria by thorough washing is driving Britain’s superbug crisis, the Royal Pharmaceutical Society warns. If everyone spent enough time on cleanliness they would be less likely to get stomach bugs and chest infections or pass on illness to others, it says.

That would cut our reliance on antibiotics that are helping create drug-resistant bacteria. A third of cases of diarrhoea and a sixth of respiratory infections could be prevented through good handwashing, the RPS estimates.

It said: ‘The recommended time to spend washing your hands is 20 seconds – as long as it takes to sing Happy Birthday To You twice.’ Yet 84 per cent of us do not wash our hands for the recommended 20 seconds, a survey of more than 2,000 people found.

Nearly two-thirds do not always wash their hands before eating, and half do not wash them after touching animals.

A third do not clean their hands before preparing food and a fifth do not always wash them after going to the toilet. Royal Pharmaceutical Society president Ash Soni added: ‘We don’t wash our hands often enough for long enough to get rid of the bacteria.

‘Even when we remain unaffected by the bugs we carry, if we don’t wash our hands we can transmit infections which then become a real problem for those who are more vulnerable, such as children and the elderly, who may then need to be prescribed antibiotics. If we can reduce the number of illnesses where antibiotics are needed, we can reduce resistance.’

Last year England’s deputy chief medical officer Dr Gina Radford recommended spending 30 seconds on hand-washing, saying that singing the first verse of God Save The Queen – the only verse most people know – was one way to measure the correct time.