Acknowledgements

Changes of policy and technology have necessitated the preparation of this new edition of the DCOM Manual for the design, construction supervision, operation and maintenance of water supply and sanitation projects in Tanzania. The 4th Edition of the DCOM Manual is expected to guide engineers and technicians in their design work, construction supervision as well as in operation and maintenance of relevant projects. The manual is to be adopted for all water supply and sanitation projects in the country. The 4th Edition of the DCOM Manual has been developed using the following approaches:

• Review of the 3rd Edition, including benchmarking with design manuals from

other countries,

• Website reviews and review of other manuals prepared by consultants who

have had working experience in Tanzania,

• Review of Literature data collection and design methods review,
• Data collection from stakeholders, namely: Primary stakeholders-MoW

technical and management staff; Private companies that deal with implementation of water supply and sanitation projects; Beneficiaries of water supply and sanitation projects,

• Collection and digitization of existing standard drawings after conversion

into metric units as felt necessary,

• Review of the 4th Edition drafts by various stakeholders including MoW staff

and other stakeholders outside the MoW,

• Revision of the 4th Edition by incorporating comments and views from all the

stakeholders,

• Preparation and submission of the 4th Edition of the DCOM Manual.

The review and updating of the 3rd Edition of the DCOM Manual is considered to be a continuous process involving regular updating to incorporate changes in policy and societal needs, emerging issues, technologies or methods. The MoW welcomes comments on this new edition of the DCOM Manual from users in order to facilitate further improvement of future editions. The new features in the 4th Edition of the DCOM Manual include mainstreaming of climate change impacts and use of various types of software in the design of water supply and sanitation projects. These features have facilitated the faster and more accurate analysis of pertinent data. The DCOM manual has also encouraged the use of Supervisory Control and Data Acquisition Systems (SCADA) for large urban and generally national projects where local capacity building can be guaranteed by the providers. It should be borne in mind that relevant software allows a wide variety of scenarios to be considered. However, it should also be noted that, despite the critical role of software/models in guiding decision�making, its limits should be realised so as to avoid its becoming a substitute for critical practical evaluation. I wish to thank the different stakeholders for their active participation and support in contributing towards the various inputs during the course of preparation of this DCOM Manual. They include those from within and outside the Ministry of Water as well as Development Partners, NGOs, Consultants, Suppliers and Contractors as well as other Ministries. The review team of engineers and technicians from MoW, RUWASA, WSSA who worked with the Special Committee for three days in March 2020 are hereby gratefully acknowledged. Finally, I take this opportunity to thank the members of the Special Committee on Reviewing and Updating the 3rd Design Manual of 2009 under the Chairmanship of Eng. Prof. Tolly S. A. Mbwette for diligently undertaking this assignment.