January 17 set off a succession of uncommon events in southeast Louisiana. First came the cancellation notices for schools. Then came ice, frozen roads, frozen pipes, and no water. Coffee houses were shuttered with no flowing potable water, hospitals and airports struggled to keep services running and home water boil advisories were issued.
First, we were advised to leave a sink trickle running, and then, in some areas, residents were warned pressure was critically low and to shut off the flow.
So how can two days of cold weather bring this region to its knees? For a large portion of Louisiana, we have built elevated homes to mitigate flooding, but that leaves our pipes under those homes outside the building insulation and unprotected.
Research demonstrates that the pipe does not break at the point where ice forms, but in the length of pipe between the frozen cross section and the valve or spigot at the end of the line. Running a thin stream of water eases pressure on pipes and prevents failure by relieving the pressure between the ice blockage and the end valve. The diameter of the pipe and its material influence freezing rates. A small-diameter pipe will freeze faster than a larger diameter pipe; copper will freeze faster than PVC.
Pipe freezes in Louisiana have historically been addressed by insulating pipes and running a thin stream of water from the tap, but these methods alone are not enough. In general, the greater the thickness of the insulation, the more resistant to heat loss the pipe will be. This method slows the loss of heat from a pipe. It could still freeze if given enough time at sub-freezing temperature, but by delaying the time to freeze, hopefully we experience a return to above-freezing ambient temperature. Second, running water at the sink tap can be effective for homes with a single potable supply line going into the home.
Dripping faucets, in combination with broken pipes, will, however, reduce pressure on municipal supply systems, sometimes triggering boil water advisories when pressure drops below 15 pounds per square inch.
So what can we do?
Homeowners, can consider:
• Heat tape, a cost-effective tape that uses electricity to heat along the length of exposed pipe.
• Freeze-resistant piping, made of materials that expand with the ice and pressure, then return to normal with the thaw.
• Going above the building code: In addition to freeze-resistant materials, other construction methods could run potable lines in interior walls, as used in colder regions of the United States.
Local government, utility services and the community need to work together to develop best practices in managing the public water supply and to encourage resilient building code to protect our potable water sources.
water quality program director, Lake Pontchartrain Basin Foundation