Dear Roshan,
Thank you very much for your inspiring message and for sharing this important milestone with us. Your vision, leadership, and commitment have been truly transformative for the global sanitation sector. The progress achieved through the Foundation’s support and your personal dedication—particularly in advancing inclusive, non-sewered sanitation and in establishing the Global Sanitation Graduate School—has left a lasting legacy that continues to empower institutions, professionals, and communities around the world.
It has been a privilege to collaborate with you and to witness firsthand the impact of your work in shaping education, capacity development, and policy dialogue across regions. I wish you the very best as you embark on this new chapter. We are deeply grateful for your partnership and friendship, and we look forward to staying connected as you continue to contribute to the sector in new ways.
Best Regards,
Hector
Thank you for your great contribution to the sanitation sector! Wish you the best in your new role!
Kind regards,
Prof. Harinaivo Anderson ANDRIANISA
Head of Department, Water, Sanitation and Hydro-Agricultural Development Engineering
Director, Global Sanitation Graduate School Regional Hub for West, Central and Indian Ocean Africa
Deputy Program Director, Mastercard Foundation Scholars Program/FILE-IN-AFRICA 2iE
Office: +226.25.49.28.00 – Mobile: +226.68.76.88.83
Dear Roshan,
On behalf of the Global Sanitation Graduate School (GSGS) Regional Hub for East and Southern Africa, I wish to express my deepest appreciation for your visionary leadership and commitment over the years. Your guidance and passion have profoundly shaped the global sanitation education landscape and inspired a generation of professionals across the Global South. From conceptualizing the GSGS to nurturing its institutional growth across 42 universities, your influence has been both catalytic and enduring. You have not only advanced inclusive sanitation but also built the systems and partnerships that will sustain it for decades. We in Africa have particularly benefited from your mentorship, encouragement, and steadfast belief that regional hubs can lead transformation from within.
As you transition into this new chapter, please accept our heartfelt gratitude. Your legacy will remain embedded in every trained professional, every research initiative, and every city now taking bold steps toward Citywide Inclusive Sanitation. We wish you joy, health, and fulfillment as you return home to your family, confident that your impact will continue to echo through the GSGS community.
Warm regards,
Dr. Rose Christine Kaggwa
Senior Director Business and Scientific Services
National Water and Sewerage Corporation
P.O Box 7053,
Kampala – Uganda
Dear Roshan,
On behalf of the Asian Development Bank Institute (ADBI), I extend our heartfelt congratulations on your remarkable career and express our deepest appreciation for your visionary leadership, unwavering commitment in the water, sanitation, and hygiene (WASH) sector, and the generous partnership you have shared with us over the years.
Your contributions over the past thirteen years at the Gates Foundation, and throughout your distinguished career, have been transformative. You have been a driving force behind a paradigm shift in how sanitation is understood, implemented, and valued. The evolution of sanitation from a narrow focus on infrastructure to a holistic, inclusive, and sustainable approach is a testament to your tireless advocacy, strategic insight, and unwavering commitment to equity and dignity for all.
ADBI has been privileged to collaborate with you and Gates Foundation in advancing Citywide Inclusive Sanitation (CWIS) across Asia. Since 2017, our partnership has become a cornerstone of regional progress in CWIS and your efforts have helped shape policy, mobilize investment, and foster innovation, especially in integrating non-sewered sanitation into mainstream development agendas.
The 2018 Development Partners Roundtable in Tokyo, the joint training programs, and the knowledge products we co-developed have left a lasting impact on public officials, institutions, and communities. Together, we have trained hundreds of public officials and produced resources that continue to inform policy and practice across the region.
Your role in influencing JICA’s integration of CWIS and non-sewered sanitation into its urban development programs, and in facilitating the transfer of Japan’s Jokasou expertise to countries like India, exemplifies your ability to bridge global knowledge with local impact.
We are especially grateful for your support in strengthening ADBI’s partnerships with Toyo University, JECES, JWSC, ASCI, GSGS, GWSC, and other institutions and for your kind recognition of our colleagues, including Dr. Seetha Ram, Takami-san, Sam, Noriko-san, and Nami-san. Your thoughtful acknowledgment of their contributions speaks volumes about your collaborative spirit and generosity.
As you return to Nepal to begin this new chapter, please know that your legacy will continue to guide and inspire us. You have left an indelible mark on our institution and on the sector as a whole. You have been a mentor, a connector, and a champion for inclusive development. While we will miss your official presence, we are heartened to know that your passion for this work continues, and we look forward to staying in touch with you in your new role as mentor and advisor.
Wishing you peace, joy, and fulfillment in your retirement, and quality time with your family, especially your mother.
Best regards,
Bambang Brodjonegoro
Dear Dr. Roshan,
Highly appreciated your kind words summarizing our long lasting collaboration since we have together completed our PhD program and entered the WASH sector over 2 decades. With such a long journey through implementing nature-based solutions for wastewater & fecal sludge treatment, co-creating reinvented toilet technologies, developing innovative tools in FSM toolbox, raising awareness on WASH with our strategic partners and especially on giving a birth of the Global Water & Sanitation Center in 2022, I have realized that you are my role model and supporter who we need many clones of yours to lead and inspire the next generation of WASH warriors. Retired from the Foundation would never stop our collaborative actions towards our shared vision on “Inclusive and Sustainable Water and Sanitation for All” by which we will be very pleased to welcome you to AIT and GWSC whenever your schedule permits. Our young and energetic team at GWSC will certainly benefit from your mentorship and generous guidance in networking potential partners and developing sustainable ventures.
We look forward to welcoming you soon at the forthcoming IWA Congress and many more missions in the near future.
With best personal regards,
Thammarat Koottatep
Professor and Co-Director
Global Water & Sanitation Center
Asian Institute of Technology, Thailand
Dear Dr. Roshan,
This is indeed big news and it’s a big loss for the world to not have you at Gates foundation.
But I totally understand your decision and hope we can continue work on something together.
I will continue to do my best on the upcoming investment on DPI.
Bests,
Dr. Chaklam Silpasuwanchai
Academic Program Coordinator l Data Science and AI (DSAI)
Assistant Professor l Information and Communication Technologies (ICT)
Asian Institute of Technology (AIT)
P. O. Box 4, 58 Moo 9, Km.42, Paholyothin Highway
Klong Luang, Pathumthani 12120, Thailand
E-mail: chaklam@ait.ac.th
Home Page: http://www.chaklam.com
Dear Dr. Roshan,
Congratulations on your remarkable journey and successful tenure at the Gates Foundation. Your contributions to advancing inclusive and sustainable sanitation globally are truly inspirational.
Thank you for your continued commitment to AIT as a valued member of our Board of Trustees. We are grateful for your guidance and look forward to collaborating closely with you for the betterment of the institute and the work we have been doing.
Wishing you a fulfilling new chapter ahead and a wonderful time with your family. I look forward to working together even more in the coming years.
Sincerely yours,
Sanjeet
Dear Dr. Roshan,
Thank you for your inspiring and heartfelt message. It is difficult to put into words how much your leadership and friendship have meant—not only to me personally but also to the entire AIT community and the broader WASH sector. While your retirement from the Foundation marks the end of an extraordinary chapter, I am truly glad that this next chapter brings you closer to your family and to Nepal, where your legacy continues to shape generations of professionals.
I have had the privilege of knowing you personally and professionally for over twenty-three years, and during this long journey, I have always regarded you as a mentor. Your wise counsel and encouragement have profoundly influenced my professional path—from identifying meaningful research directions to navigating complex institutional partnerships. Your mentorship has always combined intellectual rigor with empathy and vision, qualities that continue to inspire me and many others.
Your contribution to the global sanitation and water agenda has been transformative. Few individuals have been able to create and nurture institutions that leave such lasting impact as you have through ENPHO, the Global Sanitation Graduate School (GSGS), and the Global Water & Sanitation Center (GWSC) at AIT, to name a few. These institutions stand as pillars for innovation, capacity development, and regional collaboration, driving the shift toward inclusive, sustainable, and safely managed water & sanitation systems.
AIT and GWSC have been direct beneficiaries of your vision and commitment. Through your leadership at the Gates Foundation and your role as a member of the AIT Board of Trustees, you have been instrumental in enabling AIT’s strategic growth and relevance in the water & sanitation space. The Foundation’s long-standing partnership with AIT—spanning more than a decade—has empowered our faculty, students, and partners to lead the way in Citywide Inclusive Sanitation (CWIS), transformative sanitation technologies and data innovation, influencing more than a billion dollars in investments across Asia.
On behalf of AIT and the entire GWSC family, I would like to extend our warmest welcome as you continue your association with us in your new capacity. Your continued guidance and mentorship will be invaluable as we strengthen GWSC’s regional role and advance our joint vision of innovation-driven water & sanitation and climate-resilient urban development. I look forward to connecting with you at the upcoming IWA Development Congress in Bangkok to discuss how we can collaborate further in this new phase.
With deepest respect, admiration, and gratitude—for your mentorship, leadership, and unwavering commitment to transforming lives through water and sanitation—I wish you every happiness and fulfillment in this next chapter.
With best regards,
Dr. Sangam Shrestha
Dean, School of Engineering & Technology (SET)
Co-Director, Global Water & Sanitation Center (GWSC)
Professor, Water Engineering and Management (WEM)
Asian Institute of Technology (AIT)
P. O. Box 4, 58 Moo 9, Km.42, Paholyothin Highway,
Klong Luang, Pathumthani 12120, Thailand
Dear Dr Roshan,
Thank you for the message. Your journey is so inspiring and there is always a lot to learn from you. I look forward to working with you on the novel, innovative and much needed mission you have embarked on for AIT as we discussed. I am always thankful to you for your kind guidance. Looking forward to meeting you soon at AIT.
With Best Regards,
Professor Siddharth Jabade, PhD (IIT Bombay)
Vice President for Administration and Development
Asian Institute of Technology
Tel. + 66-2-524 5004; 66524 6005 (Direct)
Cell: + 66 82 281 3960
Hi Dai,
Beautiful message. Must be such a bittersweet time for you.
I have not seen JK in a while. I have messaged him to ask how/where he is. If you had a tough conversation, then they deserved it. Hopefully they will do better.
Will keep you posted.
Best,
Neeta
Dear Roshan-
Thanks so much for a wonderful memoir. It has been a long and fruitful association, and I am aware that we all fondly cherish the partnership. It wouldn’t have been possible without your leadership, and your relentless efforts to bring the two organizations close. We’ll miss you but the bond you have created is lasting. Best wishes for the next phase of your life, and hope we will get to meet occasionally.
Warm Regards,
Vijai Padmanabhan
DDG, ADB
Dear Roshan,
Thank you for your heartfelt message and for sharing your incredible journey with us. Your dedication and passion have made a lasting impact in the water, sanitation, and hygiene sector. It has been an honor to work with you for the last two and a half years and witness the remarkable transformation our partnership through SFPTF has achieved.
As you embark on this new chapter, I hope you find joy and fulfillment in spending time with your family and continuing to support innovation and capacity development from wherever you are. Your commitment to this mission is truly inspiring, and I look forward to opportunities to collaborate in the years ahead.
Wishing you all the best in your retirement and future endeavors. Looking forward to meeting you and Najib at the IWA Congress in December. I also look forward to working more closely with Sakshi.
Warm regards,
Jitendra Kumar Singh
Water Supply and Sanitation Specialist
Strategy and Partnerships Team
Water and Urban Development Sector Office, SD2 jksingh@adb.org www.adb.org
Dear Roshan,
I also join JK and everyone else in conveying our sincere appreciation and thanks for all the great contributions made by you in this sector. It’s been a pleasure working with you over all these years. Hope we can remain in touch.
Best wishes and warm regards,
Manoj Sharma
Director, ADB
This has been an incredible and institutional partnership that you led. Congratulations! Will look forward to staying in touch, @Roshan Shrestha
All the very best and deep gratitude for your amazing leadership and passion for the work.
Archna Vyas
Director, Gate Foundation
Dear Roshan,
Sad to hear that you will be leaving Gates Foundation. You have been an inspiration and true force to push, incentivize, support, capacitate, and enable our developing member countries to achieve inclusive sanitation.
I have no doubt that you will continue inspiring and supporting all, no matter where you are. Thank you being our partner for so long.
Best regards,
Neeta Pokhrel
Director
Water and Urban Development Sector Office
Pacific and Southeast Asia Team
Dear Roshan,
Great to hear from you! It was my sincere pleasure working with you on NSS over the years across South Asia– we did some great work together. What a ride it’s been : ).
Wishing you all the best in your next steps. Stay well friend!
Ron H. Slangen
Deputy Country Director
Viet Nam Resident Mission
Asian Development Bank
Ha Noi, Viet Nam
Phone: +8424 3933 1374
Dear Roshan,
Your message is very touching. While it’s hard to see you leave the Gates Foundation, I want to take this moment to celebrate your extraordinary contribution and lasting impact on the sanitation sector in Asia. You have changed the way countries, cities, and partners think and act on sanitation—bringing political attention, stronger institutions, and real investment where it matters most.
It has been a remarkable journey, and I am proud of what we have achieved together. You have been not only a visionary leader and trusted partner but also a good friend. Your dedication, humility, and passion have inspired so many of us at ADB and beyond.
You are a true legend in this field, and I have no doubt that wherever your next chapter takes you, you will continue to inspire and lead. Wishing you all the very best for this exciting new stage of life—and I look forward to staying in touch and crossing paths again soon.
With warm regards and great appreciation,
Ms. Jingmin Huang
Director
East, Central and West Asia Team
Water and Urban Development
Sector Office Sectors Department 2
Asian Development Bank
6 ADB Avenue, Mandaluyong City,
1550 Metro Manila, Philippines
Tel: (632) 8632 6181, Fax: (632) 8632 2443
Email: jhuang@adb.org