Those companies aren't utility companies though.

The main, monopolistic solution of municipal water certainly is. The point is that options can still exist in a monopoly. Google still has a monopoly despite the existence competitors.

Most apartment buildings won't let you store large amounts of water on property.

That's not even remotely comparable.

Firstly it's not structurally practical to store giant tanks of water on private property. So the comparison makes no practical sense anyway.

But more, there is a significant market for private water in other properties. It's a non-trivial market which serves a significant proportion of the US population.

There is no significant market for private/non-Google search. Not only is DDG a footnote, but Google's dominance forces businesses to take steps to optimise their Google rank - or face penalties by losing access to potential customers.

Google can also remove businesses who aren't even customers from its rankings on a whim, with no redress.

It's clearly a monopoly.

When I lived in China, I didn't have the luxury of having access to Google, so I used Bing instead. It was actually quite reasonable for most of my needs, I'm not sure why more people don't give it a go. Of course, now that I live in the states again, I use Google, but most of my searching is on YouTube anyways (which was something else I didn't have access to in China).

I'm pretty sure those same apartment buildings wouldn't let you set up the large scale server farm required for you to set up your own search engine alternative to Google either.