Preventing Pipe Freezes with Running Water

February 14, 2023

Bryan Smith
Area Extension Agent-Agricultural Engineer

Caption: A dripping faucet may help prevent freezing during cold weather. Image source: Freeimages.com

We do not often see sub-20 degree weather in the Piedmont, but when we do many people immediately become concerned about pipes freezing in their home.  Several sources recommend allowing a faucet in the house to run continuously to help prevent freezing, with a pencil-lead-thick stream of water flowing from the faucet.

We measured the flow rate of this pencil-lead-thick stream of water flow in our Extension Office to see how much water would actually be used in this practice.  The stream filled a 12 ounce cup in 1.8 minutes.  There are 128 ounces in a gallon, so using this conversion we were able to calculate the flow rate from the faucet of approximately 3 gallons per hour.  Now let’s talk about homes using wells and homes using city or county water.

If a home has a standard well with a 40 gallon bladder tank, the actual “drawdown” amount (the amount of water that leaves the tank from the time the pump turns off until it turns on again) for the tank is about 13 gallons of water.  If the homeowner left one faucet running with a pencil-lead-thick water stream, the well pump will probably turn on once every 4.3 hours (with no other water use).  Typical pump run times to refill a pressure tank are in the 2 to 3 minute range, so the electricity use would be minimal.  Quite frankly the homeowner may want the pump to turn on a bit more often than every 4 hours.

If a home uses city or county water the concern will be about the increased water bill.  3 gallons per hour from one faucet translates into 72 gallons of water per day.  For comparison, a normal SC household uses about 120 to 150 gallons of water per day per person.  So a single running faucet may add 12% more water cost per day used for the home, which is very minimal since the intense cold front may only last two or three days.

Regardless of the home water source it will be fine to leave one or two faucets running during a sub-20 degree cold snap.  The moving water will help prevent freezing, and the amount of water or electricity used will certainly not break the bank.  Homeowners may find that allowing two faucets to flow in this manner will more adequately prevent pipes from freezing.