Today, there's a front page NY Times story about the future of the New York City water supply - and whether the city will need to build an $8 billion filtration plant to keep the water clean. Some people may have been surprised to realize that chemicals are currently added to our water to filter out the impurities, but this is considered a stopgap measure, because turbidity (water cloudiness) from upstate water supplies is getting worse. The Times describes water up there looking "like a chocolate Yoo-hoo." The article details the different areas the city receives water from, which we need to re-read again to full understand. But the end of the article was clear:
Which raises the question of whether building a filtration plant is inevitable in the long run, and if so, wouldn’t it make more sense to simply go ahead and build it now?
City, state and federal officials don’t think so. Mr. Mugdan, the federal official, calculates that the city has spent about $1 billion over the last decade to protect the water supply, compared with $6 billion to $8 billion to build a plant, along with hundreds of millions of dollars in operating costs.
“Even if, 75 years from now, some accountant asks how much has it cost the city to avoid filtration versus how much we would have spent to build it,” Mr. Mugdan said, “we’ll still be ahead.”
So, there you have it. Stopgap measures have their place, perhaps.
We're going to ask our favorite civil engineer (our dad!) about this article, but in the meantime, you can learn a little about water purification by reading the Wikipedia explanation of water purification and this paper about the history of the city's water supply system. And you can read about water quality at the City's Department of Environmental Protection website. On the bright side, our reservoir has a lot of water!