PurposeThe sixth of the global Sustainable Development Goals (SDGs) has access to improved sanitation as one of its targets. Sanitation is important not only for environmental quality and public health but also for the outstanding universal value (OUV) of heritage monument sites and tourism promotion. The study examined the causes of open defecation (OD) in the neighbourhood of a World Heritage (WH) site in Ghana and the implications of the practice for sustainable tourism and heritage management.Design/methodology/approachThe study used the qualitative approach. Data were gathered from purposively targeted respondents (an Environmental Health Officer, Heritage Managers, a Tourism Expert, Hoteliers, Zoomlion Staff, Open Defecators, Community Opinion Leaders and Ordinary Community Residents) and analysed using the thematic approach.FindingsIt became evident that the causes of OD were: the lack of toilet facilities in many houses in the community, filthy and foul-smelling public latrines, poor attitude and heritage culture, mental and income poverty, inadequate sensitisation and a poor law enforcement regime. OD threatened the sustainability of heritage tourism and its associated livelihoods, as well as public health. In addition, it impaired the authenticity and integrity of the heritage monument, culminating in a detraction from the OUV of the heritage property.Practical implicationsIn collaboration with the local, national and international stakeholders, the managers of the heritage monument should design and implement a comprehensive environmentally friendly plan. The plan should consider demarcating the boundaries of the heritage asset, monitoring the protected area, enforcing sanitation laws and mounting intensive sanitation education campaigns. It should also consider providing a decent toilet in the vicinity of the monument for the transit population, facilitate the provision of a toilet in every house through the community-led total sanitation approach, installing digital cameras at vantage points in the buffer zone of the castle to capture open defecators and punishing offenders severely to deter others from engaging in the ignoble practice of OD.Originality/valueThe authors argue that sanitation at heritage sites in developing countries merits further discussion within the WH network to promote sustainable heritage conservation management and tourism.