Access to Potable Water
Access to Potable Water

A reliable source of potable water is essential if a building is to remain livable during a power loss.

Description + function


Standard municipal water pressure may be adequate to keep buildings up to 6 stories high supplied with water during of a power outage. Taller buildings typically either use pressure-booster pumps or pump water to a roof tank.

Strategy into action

Rooftop water tanks.

During an outage, buildings with rooftop water storage have a resilience advantage since their water supply is gravity-fed and may last for days if residents know to strictly curtail water use. Structural considerations may make the retrofit installation of rooftop tanks difficult.

Many taller residential buildings have rooftop water tanks. During an extended loss of power, pumps are unable to replenish the water in the tank.
Image: Alexander Rabb.
Emergency water faucet.

Many water pump systems have a bypass valve which enables the building to bypass the pumps and run water to lower floors. The emergency water faucet should be located in a public place close to the municipal water supply entrance.


A low-flow showerhead.
Image: Wil C Fry.


Water efficiency measures.

Efficient toilets, showerheads and faucet aerators pay back their installation cost quickly, and reduce the amount of water used during emergencies. Leaks are also a large source of waste. Repair all leaks immediately, and encourage residents to report leaky fixtures.

Critical-load circuits.

If the building has a water pump, consider adding it to the critical loads served by a backup generator.

Rainwater storage.

Storage tanks and rain barrels can provide water for non-potable uses during emergencies. Rainwater should be treated as greywater and used only as code allows. Tanks should be enclosed to keep out mosquitos and other pests, and cleaned out once a year.


A rain barrel connected to a building downspout.
Image: Arlington County.
Drinking water storage.

Keep a water cooler with multiple containers of spring water on-hand, or store cases of bottled water. Plastic containers of water should be stored in a dark location protected from freezing and leeching. Encourage residents to store emergency bottled water or store tap water in clean containers and bathtubs.

Ask your plumber for recommendations about backflow preventers to avoid contaminating the municipal water supply. A licensed plumber can help select a proper device.

Operations + maintenance


Water storage systems need regular flushing and cleaning, even for non-potable uses. Check with the local health department to see if special permits are required for potable water cisterns.

Store several clean water containers near the emergency faucet for unanticipated power outages.

Estimated cost


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Supporting strategies



Case Study: Emergency Water Connection

Case StudyEmergency Water Connection


The Verdesian is a multifamily residential building in lower Manhattan.


The building installed an emergency water faucet on the ground floor above the DFE. The faucet bypasses the roof tank pump and connects directly to the municipal water supply, assuring a reliable source of potable water even during an extended power outage.


The backup water valve was added during an extensive resilience retrofit at minimal cost.

The emergency faucet has hook-ups for both fire and regular hoses.

Images: Samantha Yost.
211 North End Ave.
New York, NY
253 Units
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