A widely shared online tip suggests placing a copper penny in a bird bath to prevent algae growth, but UK gardeners are being warned that only pre-1982 pennies are safe. Pennies minted after 1982 are mostly zinc, which can corrode in water and release toxic levels of zinc that may poison birds.
The Penny Hack Explained
The technique, popularised on social media, involves dropping an old penny into the base of a clean, water-filled bird bath. The user gigisgardens posted a video demonstrating the method, which has amassed over 80,000 views. The video caption explained: "Head of the penny hack to keep algae out of your bird bath? It works by please use the right penny."
Pennies produced before 1982 are composed largely of copper, which has natural antimicrobial properties that help slow algae growth. However, the caption warned: "But pennies made after 1982 are mostly zinc, and if they corrode in water, they can release zinc into the birdbath. Even small amounts of zinc can be toxic to birds, leading to metal poisoning. Always check the date before dropping a penny in your birdbath—the birds' health depends on it."
Viewer Reactions and Alternative Options
The clip generated hundreds of responses. One commenter noted: "Not everyone knows that it can't be just any old penny. There are also copper discs you can buy for bird baths." Another wrote: "I have an old penny in my bird bath and it's stopped the algae growth completely." A third added: "I use this trick, but also wash my bird bath out every day in the summer."
RSPB Cleaning Advice
The RSPB (The Royal Society for the Protection of Birds) advises using a ready-to-use spray cleaner that is safe for bird feeders and baths. It should be applied regularly and scrubbed thoroughly to remove marks and algae. The RSPB stated: "Disease has been linked to population declines in some species, and dirty feeders can harbour pathogens and increase the risk of cross-contamination between the birds that visit them. Keeping on top of your cleaning regime will help prevent the risk of spreading disease."
If a specialised cleaner is not available, a soapy washing-up liquid solution can be used, provided it is thoroughly rinsed away before refilling the bath.
