Researchers have found that adding lime juice to water while using a solar disinfection method removed detectable levels of harmful bacteria such as Escherichia coli (E. coli) significantly faster than solar disinfection alone.
Prepper concerns aside, this has practical application for in low-income regions, where solar disinfection of water is one of several household water treatment methods to effectively reduce the incidence of diarrheal illness, right now. One method of using sunlight to disinfect water is known as SODIS (Solar water Disinfection). The SODIS method requires filling 1 or 2 plastic bottles with water and then exposing them to sunlight for at least 6 hours, though in cloudy weather, longer exposure times of up to 48 hours may be necessary to achieve adequate disinfection.
"For many countries, access to clean drinking water is still a major concern. Previous studies estimate that globally, half of all hospital beds are occupied by people suffering from a water-related illness," said Kellogg Schwab, PhD, MS, senior author of the study, director of the Johns Hopkins University Global Water Program. "The preliminary results of this study show solar disinfection of water combined with citrus could be effective at greatly reducing E. coli levels in just 30 minutes, a treatment time on par with boiling and other household water treatment methods. In addition, the 30 milliliters of juice per 2 liters of water amounts to about one-half Persian lime per bottle, a quantity that will likely not be prohibitively expensive or create an unpleasant flavor."
Researchers wanted to determine if one of the active constituents in limes known as psoralenes could enhance solar disinfection of water, so they looked at microbial reductions after exposure to both sunlight and simulated sunlight. The researchers filled polyethylene terephthalate plastic bottles with dechlorinated tap water and then added lime juice, lime slurry, or synthetic psoralen and either E. coli, MS2 bacteriophage or murine norovirus.
They found that lower levels of both E. coli and MS2 bacteriophage were statistically significant following solar disinfection when either lime juice or lime slurry was added to the water compared to solar disinfection alone. They did find however, that noroviruses were not dramatically reduced using this technique, indicating it is not a perfect solution.
But when the apocalypse comes, the perfect need not be the enemy of the good, right? Of course, you may not be in an area where Persian limes grow on trees. The researchers say they want to study lemon or other acidic fruits next. Luckily, the sun still works without any fruit at all.
Published in American Journal of Tropical Medicine and Hygiene.