If we're going to be strictly factual about it, Google is actually spending money on cancer research and spaceships;
http://www.columbia.edu/cu/news/oncampus/08/10/google.html describes one of a number of grants that are going to researchers on, among other things, cancer; Larry Brilliant himself suffered from thyroid cancer. Also, Google bought SpaceShipOne, which is now on display at the Googleplex. Presumably Scaled Composites is using the proceeds from the sale for spaceship research. Sergey is going to space in a private space flight next year, assuming all goes well:
http://www.spaceadventures.com/index.cfm?fuseaction=news.vie...There are many other investments in cancer research and space travel being made by individual Googlers.
However, it is perhaps more to the point that both Google Search and Google Academic are crucial research tools for medical research and for aerospace engineering, as for many other fields.
Both directly and through its employees, Google is also funding substantial applied research in crucial areas such as renewable energy production, genomics, public health, and ground transportation.
I don't know what you mean by "disastrous public plumbing in the US". My experience with US municipal water supplies and sewers during the 29 years that I lived there was that they were inexpensive, reliable, safe, and efficient. My experience with water supplies (and sometimes sewers) in other countries has been much worse.
A personal note: I haven't ever tried to work for Google because of, essentially, ethical concerns: I am in danger of having to live in a world where a large fraction of our communications are intermediated by a single company, and I think Google's cultish secrecy is corrosive to the values of Silicon Valley. However, I think Google should only be dinged for its real faults, not imagined ones.