The practice of allowing water taps to remain in the ‘on’ position during a water supply interruption involves positioning the handle or knob of a faucet such that it would permit water flow if supply were present. This action is often considered in anticipation of the return of water service following maintenance, repairs, or other disruptions. The goal is to potentially mitigate certain issues related to air and pressure within the plumbing system.
A primary consideration for this practice stems from the potential for airlocks within water pipes. When water service is restored, air trapped in the plumbing can create pressure imbalances, impede water flow, or cause sputtering from faucets. Leaving faucets open may assist in the escape of this trapped air, theoretically allowing water to flow more smoothly upon restoration of service. Historically, this was a more common practice due to variations in plumbing infrastructure and water distribution systems.