Pakistan's irrigation system is one of the world's largest -- serving over thirty million cultivated acres on approximately three million farms. This chapter examines certain efforts of Pakistan's farmers to cope with this pressure through transactions between farmers involving irrigation water supplies. Canal water trading necessitates an informal reciprocity relationship which, in turn, requires trading partners to develop trust among themselves. The chapter describes water transactions that are local in nature and nearly always between farmers who share a common outlet from their watercourse. Measurement of watercourse improvement dictated that the sample survey included both improved and unimproved watercourses. The nature of delivering tubewell water to buyers also tends to encourage trade of irrigation turns. Buyers of tubewell water arrange with an upstream tubewell owner to pump into the watercourse during their turn. The empirical evidence suggests that private tubewells tend to encourage cooperation among farmers on Pakistani watercourses.