Good idea. A similar note about my understanding of the issue: I am quite limited in my knowledge of water management that isn't Dutch, so part of my understanding comes from Wikipedia.

Do you refer to this part?

So now we're entering a period where many of the water pipes and treatment plants built throughout the 20th century are falling apart and need to be replaced at almost the exact same time. This puts a tremendous financial strain on our water utilities, and they're really limited on how much they can raise our water rates, because no one likes their water bill going up.

NIMBYs become a secondary problem when an entire city depends on a couple of people living near something that smells. Isn't it important enough for the city to overcome some locals? I get that there are a lot of local factors at play here, but I mean, if we can do it like this... there must be a way.

Sidenote: holy balls y'all use a shitload of water. The average daily consumption in America is 340L (90 gallons) per capita. Even the rainiest state, Louisiana, still uses 300L (80 gallons) per capita. Average Dutch person uses 140L (33 gallons) per day...

3) I also had my doubts about the decentralisation part. Economies of scale are often undervalued. I do find it ridiculous that you can't install cisterns. Are rainwater barrels illegal, too?

STORY TIME:

Researching this topic reminded me of a fun story about Dutch water boards. Water boards were the first forms of local government here, some going all the way back to the 13th century. Farmland kept getting flooded, so farmers got money together, built dikes around their lands and managed the water. This required agreement between the farmers: who's paying to build the dikes, and to keep them up? Hence the birth of water boards way before anyone had ever heard of Willem the First.

Later, with the invention of the windmills, we went on a goddamn poldering spree. Build a dike around a lake, dig a canal to the nearest river, put some mills on the edge and you have the most fertile land in western Europe. Half of the country (and I mean this literally) was poldered. This was the area north of Amsterdam before polders came into picture:

And this is after. Notice the complete lack of lakes?

Thus there were hundreds of water boards, all protecting their polders. The massive poldering and canal-digging led to amazing crop yields, which led to the Netherlands becoming super awesome in trade and which led to a Golden Age in the 17th century. But the more industrialized the country became (we're skipping three centuries here), the more water boards merged. There were 2500 water boards in 1950. Now, there are only 25:

So, you know, all the smaller water boards merged into bigger ones, right? Well, not all of them. See that no. 25 all the way in the North? That reaaly small square next to it? That is Waterschap Blija Buitendijks, which controls an area of a staggering one square kilometer. They've existed for over a hundred years, and didn't want to merge because they wanted to take a different direction in water management, for their one square kilometer. So they still have an office in the nearby village, and can still act completely independent of all the other water boards. Their office burned down last year (something something irony) but they got it rebuilt.

It's like a small village in Gaul that just won't bulge under the pressure of the Romans. I love these kinds of administrative oddities.