The Delaware Aqueduct is the world’s longest tunnel and an engineering marvel, delivering water 85 miles to the city using only gravity. However, a portion of it travels through soft limestone and this has become a problem. A small stretch has been leaking water for decades – up to 35 million gallons per day, or more than 3% of the city’s water consumption.
From 2015-2019, NYC will be constructing an 8-mile bypass tunnel around these leaks. During most of this construction the Delaware Aqueduct will continue delivering water, but at some point it will need to close to make the connection to the bypass. Read the details from the Department of Environmental Protection here.
How will New York function with 50% of its water supply turned off? Thankfully, by the time the Delaware spigots close, those at the new Croton Filtration Plant will open. Right now, 10% of our water comes from Croton; when the plant is completed, it can supply 30%. The city has a few other tricks up its sleeve like moving water between various reservoirs and relying on groundwater supply in Queens. The challenge is also mitigated thanks to a 2010 law that increases water efficiency standards for new plumbing fixtures (a Green Codes Task Force recommendation). However, it seems probable that there will be some restrictions on water use that year, such as limits on water for landscaping. Without restrictions, NYC might be forced to “borrow” water from neighbors in New Jersey and Long Island.
From time to time I’ve heard the sentiment that thanks to climate change, we no longer need to worry so much about water efficiency in New York. This theory is that our region is getting wetter, which is why we haven’t had a drought in 10 years. That may be the case, but I wouldn’t want to bet my money – or my drinking water supply – on what the weather forecast predicts for next week, never mind years out. Let’s not lose sight of the fact that water efficiency ensures we aren’t needlessly wasting resources and enables us to operate our drinking water infrastructure below capacity, giving us critical breathing room at times like the closing of the Delaware Aqueduct.