That uncertainty is not a modern hedge; it was already present when the well was first written about in any detail. The account comes from a Mr White, who noted in 1919 that when he came into occupation of the property in 1873, some of the older local people already regarded it as a sacred site, calling it "St Brow's well" and coming to collect water they believed had curative properties. White himself was candid about the limits of this claim, writing that there was "no authority for calling this a holy well except this tradition." The well does appear on maps associated with an old lease of the land, though in a position slightly different from where it stands today, which adds a minor cartographic puzzle to the site's already uncertain status.

The site sits on what were formerly the grounds of Ballinguile House, a property that preceded the housing estate now occupying the land. Scholarly attention has focused on the question of which saint, if any, the well might be connected to. Researchers Ó Danachair (1958) and Daly (1957) both associated it not with the well-known St Mobhi of Glasnevin, a male saint whose monastery gave its name to that part of the city, but with a distinct figure: St Mobhi the nun, associated with the parish of Donnybrook. Holy wells in Ireland were commonly dedicated to local saints, often obscure ones whose cults survived in place-name memory and folk practice long after any formal ecclesiastical recognition had faded, and the Donnybrook well seems to be precisely this kind of site, its identity kept alive more by neighbourhood habit than by any written record.

The well is within the Eglinton Square estate, so access depends on navigating a modern residential development rather than open countryside. The tower-like covering structure is the clearest marker of the well's presence. There is no formal heritage signage to guide a visitor, and the site sits quietly within an ordinary suburban setting, which means it rewards the kind of attention you have to bring deliberately. Given the ambiguity that has surrounded it since at least the 1870s, arriving with low expectations of certainty is probably the right approach.