Four Deworming charities? I get their methodology. I know it sounds good to focus only on practices that have solid evidence of their effectiveness, but there are other factors to consider.

For example, yes deworming is extremely effective and easy to implement. You give the individual some medication, you can watch them take it, count how many doses, calculate cost per person, etc. But it's a short victory unless we are asking "where are the worms coming from?" and address water quality as well.

With a water project though you have so many more variables that are more complicated to measure, but I think we'd agree that clean water probably has a greater impact in the long run.

Evidence based approaches break down even more when you try addressing the real root causes too. Try looking at income generating projects or agriculture. All require so much contextual knowledge and are so site specific that there can't be one single approach. However I think we'd all agree that people having the ability to provide for themselves is a much greater good than being dependent on a charity for deworming medication.