If you’ve successfully flushed a toilet recently, then you appreciate (at least subconsciously) the workings of a good sewer system. Waste disappears, no matter what time of day or night, or what the weather’s like.

But weather is actually a challenge for a sewer system, especially precipitation. That New York City’s sewers can handle the waste of more than 8 million residents on a daily basis—plus the occasional downpour or major storm like Hurricane Irene—is a testament to its resilience.

Read more via The Slate