Septic tank
While a properly maintained and located septic tank does not pose any more environmental problems than centralized municipal sewage treatment, certain problems can arise with septic tanks in unsuitable locations. Since septic systems require large drainfields, they are not suitable for densely built areas.
Bon Secours Mother and Baby Home
Corless's original research noted that the site was also the location of a septic tank when overlaid with maps of the period of use as a workhouse. The 2017 report by an Expert Technical Group, commissioned by the Department of Children and Youth Affairs, confirmed that the vault was a sewage tank after reviewing historical records and conducting a magnetometer survey; it concluded, "The combination of an institutional boarding home and commingled interments of juvenile remains in a sewage treatment system is a unique situation, with no directly comparable domestic or international cases."