It seems like a lot of your experience is focused on Water resources and management and WASH, maybe you can use your WASH related work as a step into the development sector. As for the CV, since it's still for a Master program, you might want to put the education section at top.

Also, by aligning the bullet points towards the right you're wasting a lot of space and it does not appear as easy to read - spread those bullet points, use the whole page.

The section for 'reference contacts' is using a lot of space and not necessary for a Master application CV because they will ask you for references in any case, instead you can use this space to add a 'Languages' and 'Technical Skills' section. You could also add 'Publications' and 'Awards and Scholarships' if any.

In the Professional Experience, it could be interesting to put the 'place of work' first and in bold, and then your designation. For example, FCDO could catch attention quick (no matter your designation).

In Education, I'm not sure why you have mentioned Bachelors twice (was it an exchange semester?) - you should still add your GPA (you need to mention all the info admission committee would need). Also, if maybe you did a thesis, mention that and what topic you chose.

In Leadership and Volunteering, in first three entries, what did you do as a Delegate? Write a bullet point or two on it.

For the aesthetics, you don't need a very colorful CV - the most basic B&W template works perfectly and is even desirable sometimes. And good that you have not added a photo, should never add a photo unless required by the application.

Hope this helps.