The information above is taken from the University of Ontario 'World's Largest Cities' pages and regrouped to show the extent of the challenge facing Africa in particular - the number of cities in Africa in the 'top twenty' going from three at present to 13 projected in 2100. Note the potential size of some of those cities in 2100 .... & yes, I understand the projections have taken into account significantly reducing total fertility.

Amongst all the other issues facing these cities, water and sanitation service delivery, backed up by developed water resources of course, requires billions of whatever currency you chose in new CapEx - that is investment. The fashion for 'hybrid' 'innovative' financing, I believe, is simply not affordable when you consider commercial interest rates relative to the risk of interest payments (let alone loan principal repayment). Even concessionary finance is going to be a challenge. If the world is serious about achieving SDG6 (let alone all the other, equally important SDGs) then donor 'transfers' as grants will be necessary.

Good therefore to see from Devex that "The [French] commitment to quadruple the budget for grants to €1.3 billion ($1.5 billion) in 2019 won praise from civil society. "This is definitely a step in the right direction … but we're starting at a very low level," said Friederike Röder, EU and France director with ONE. France committed to spending 0.55 percent of GNI on official development assistance by 2022. (Devex, This week in development, Anne Paisley, 6 September 2018)