Development of an MS Excel Visual Basic for Applications (VBA) program for water distribution network (WDN) design is presented in this paper. The tool solves a given closed-loop WDN by Hardy-Cross algorithm. Both VBA programming and MS Excel's data validation modules are employed to provide easy-to-use environment for engineers and also in the education of engineers, and moreover, software solutions in the market are expensive and hard to obtain. A step by step solution to a part of Uskudar which is a county of Istanbul network is also provided. The color-coded instructions for the correction of the network system will be helping for the users. The tool is open source and can be used for the design of WDNs by engineers and students.