Kenya’s County Climate Change Fund (CCCF) is financing public good investments focused on the water sector to increase the resilience of communities to climate change. In the drylands, investments in water are critical for water and food security, yet ensuring the functionality and sustainability of water investments remains an ongoing challenge. This paper assesses the functionality and sustainability of 62 CCCF water investments in five dryland counties (Isiolo, Wajir, Garissa, Kitui and Makueni) in Kenya through a functionality survey and stakeholder workshops. The survey was designed based on a review of studies assessing the functionality of water supply systems. Across the five counties, 62.9% of investments were functional compared to 37.1% non- or partially-functional. The main factors that contributed to non- and partially functional investments were poor siting, poor design and workmanship, damage due to vandalisation, and lack of repairs and maintenance. Exploring the underlying causes of poor functionality revealed a complex mixture of technical, social, institutional, environmental and governance deficiencies. To improve the functionality and sustainability of water investments, especially as the CCCF is scaled out further in Kenya, emphasis on the ‘hardware’ aspects and establishing new water points, should shift towards operation and maintenance (O&M), rehabilitation of existing water points, improved governance, monitoring and evaluation (M&E), and other ‘software’ aspects