In recent weeks, people all over the world have been settling into a ‘new normal’ of restricted mobility, online working, social distancing and enhanced hand hygiene. As part of the global fight against the spread of COVID-19 (the illness caused by SARS-CoV-2), we are repeatedly reminded by public health authorities that frequent and thorough hand-washing with soap and water is one of the best ways of limiting transmission. The rationale behind this is clear: washing regularly and thoroughly physically degrades and removes viral particles from hands, and therefore lowers the likelihood of infection transmission. Many health agencies are recommending washing hands for a minimum of 20 seconds up to 8–10 times per day. If washed in running water, the average hand basin tap uses 2–3 litres per minute, which implies a total water requirement of 8–10 litres of clean water per person per day, as well as appropriate soap and drying facilities (i.e. not a reused and possibly contaminated towel or rag).