During the construction phase, collaboration among project parties involved in the contract is a crucial factor for effectively delivering infrastructure projects. Yet, while researchers have assumed that implementing collaborative contracts will enhance collaboration, practically, there is evidence this is not always the case. This research investigates the challenges and opportunities of collaboration between organizations across the “office” and the “site” through a qualitative study of Australian water infrastructure projects utilizing collaborative contracts. To ensure a more focused approach to data collection and analysis, this research specifically examines the collaboration between clients and contractors among all organizations involved in office-based and onsite practices. By analyzing interviews with experts involved in these projects, the findings reveal three main areas where challenges and opportunities arise in collaboration under collaborative contracts during construction: contract implementation, collaboration competencies, and systems and processes. This research enriches the knowledge body by providing deeper insights into the distinct collaboration challenges and opportunities to address change events. While interviewees generally appreciate the opportunities provided by the contractual framework, they also highlighted specific challenges they faced in this area. However, they primarily struggle with issues related to collaboration competencies and systems and processes across the office and the site.