Acknowledgements

Changes of policy and technology have necessitated preparation of this new edition of the DCOM Manual for design, construction supervision, operation and maintenance of water supply and sanitation projects. The 4th edition DCOM Manual is expected to guide engineers and technicians in their design work, construction supervision as well as in operation and maintenance. It is to be adopted for all water supply and sanitation projects in Tanzania.

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 worked in Tanzania,
• Review of Literature, data collection and design methods review,
• Data collection from stakeholders: Primary stakeholders-MoW technical and management staff; Private companies that deal with implementation of the water supply and sanitation projects; Beneficiaries of water supply and sanitation projects,
• Collection of existing standard drawings and digitisation after conversion to metric units for some drawings,
• Review of the 4th edition drafts by various stakeholders: MoW staff and other stakeholders outside 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 DCOM Manual is considered to be a continuous process whereby regular updating is needed to incorporate changes in policy and societal needs, emerging issues or technologies or methods. The MoW welcomes comments on this new edition of the DCOM Manual from users to facilitate further improvement of future editions.

Among the new features in the 4th edition DCOM Manual include mainstreaming of adaptation to impact of climate change and use of various types of software in design of water supply and sanitation projects. These facilitate faster and more accurate analysis. The DCOM manual has also encouraged use of Supervisory Control and Data Acquisition Systems (SCADA) for large urban or national projects where local capacity building can be guaranteed by the providers. It should be borne in mind that software can allow a wide variety of scenarios to be considered. However, it should be noted that despite the critical role of software/models in guiding decision-making, its limits should be realised so as to avoid that it becomes a substitute for critical practical evaluation.

I wish to thank the different stakeholders for their active participation in contributing various inputs during the course of preparation of this DCOM Manual from within and outside the Ministry of Water including Development Partners, NGOs, Consultants, Suppliers and Contractors as well as other Ministries for their support.

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.

Prof. Kitila Mkumbo Permanent Secretary Ministry of Water 14th March 2020

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