Its Irish form, Tobar Feille, translates as "well of the treachery", yet locally it was known as Tobarín Donn, "the little brown well", and a tradition collected from Rahavanaig School tells of soldiers washing battlefield wounds in its water and being immediately cured. That same tradition notes that when people began drawing from it for ordinary household use, the well and its associated statues quietly disappeared. Whether the treachery of the name refers to a long-forgotten act or to the well's eventual loss of standing is not recorded.

The water itself is chalybeate, meaning it is naturally impregnated with iron salts, which gives it a faintly mineral quality and accounts for its reputation as a healing source. Writing in 1756, the antiquarian Charles Smith recorded that the well was named after the man who first identified its properties, and that this individual tested its usefulness in scorbutic cases, comparing it favourably to the German spa waters then fashionable among those who could afford them. Scurvy, caused by vitamin C deficiency, was a common enough affliction in rural and maritime communities of the period, and chalybeate springs were widely believed to offer some relief, whatever the actual mechanism. By 1943, when an Irish Tourist Association survey was conducted, the local belief in the well's curative powers was still described as strong. The well appears on Ordnance Survey maps from both 1841 to 1842 and 1914 to 1915, marked consistently as Toberfell, suggesting it retained a recognised identity across those decades even as its active ritual use appears to have faded.