Aims: The COVID-19 pandemic presents the opportunity to learn about solitary drinking as many people were forced to spend time at home. The aim of this study is to examine the relationship between solitary drinking and living without other adults on alcohol consumption. Methods: A longitudinal study with four survey waves (between May and November 2020) obtained seven-day drinking diary data from Australian adults living in New South Wales. In May, a convenience sample of 586 participants (Mage = 35.3, SD = 14.8; 65.3% women) completed the first wave. Participants then completed a survey in June (n = 319, 54.4% response rate), July/August (n = 225, 38.4% response rate), and November (n = 222, 37.9% response rate). Information about alcohol consumption including risky drinking (more than four drinks on one occasion), household structure, solitary drinking, and demographics were collected. We conducted random-effects panel bivariate and multivariable regression analyses predicting the number of standard drinks and risky drinking. Results: Participants with solitary drinking occasions consumed more and had more risky drinking occasions than participants with no solitary drinking occasions, which was also found to be the case during lockdown. Living without other adults was associated with less consumption and less risky drinking than living with other adults. However, participants who lived without other adults and had frequent solitary drinking occasions (solitary drinking in >50% drinking occasions) reported more consumption than participants without a solitary drinking occasion. Conclusions: Individuals who consume alcohol alone and live without other adults or spend long periods of time at home may be more at risk of alcohol-related harm.