Today water pressure in the western world is mostly generated by running finely controlled electric pumps constantly, but it wasn't too long ago that water towers were used everywhere to maintain water pressure. The advantage of a water tower is that you can run an inaccurate oversized pump occasionally to fill up the reservoir on top of the tower, and gravity does the rest of the work.
Of course building a tower capable of holding many tons of water is a comparably complex civil engineering task and is costly in materials.
In most cases it's not. You park a ground level tank on one of the taller hills in town.
>It requires skilled engineers and labour
Exactly, and there are no tricks around that are known to solve that, other than to engage in massive infrastructure projects. A very simple thing.
When you have a serious issue in production that can be fixed with a global variable in 5 minutes or spending a day correctly planning and implementing a fix that routes the data correctly, what do you pick? I'd hope doing the first thing and replacing it with the second.
It's that sort of decision, only people die if you don't move in time.
I also assume that to ensure water pressure involves electricity - a lot of poorer countries do not have a constant or reliable electricity supply.
Building this sort of infrastructure is a massive engineering task and it can take years to complete a project like this. It requires skilled engineers and labour. During that time, people will die because it's not done yet.
In conclusion, I think Gates and co have made a good investment.