A dementia patient can no longer live at home safely when their care needs exceed what can be provided in that environment. Key indicators include the inability to manage personal care independently, repeated falls or accidents, significant wandering behaviour, severe sleep disturbance, inability to eat or drink adequately without full supervision, frequent infections or hospital admissions, and carer exhaustion that has reached breaking point. The decision is typically reached after a period of increasing difficulty rather than at a single clear moment. A formal care needs assessment by the local authority is the recommended starting point.