Reading a cubic foot analog water meter – A simple conversion to gallons per minute

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All too often when a homeowner is notified of a hidden water leak issue it’s often a good idea to know how to quantify how big the leak really is.

Analog meters will typically have a clock hand that travels around the circumference of the meter face. The spinner star of triangle is a visual aid only that is often referred to as a leak detector because it will visually turn with the slightest of water flow. The clock hand however is an actual measurement tool. Around the circumference of the meter face you will likely see 10 digits as the photo below shows. One full revolution of this clock hand equals one cubic foot of water. Once CF of water is 7.48 gallons. Each digit around the face represents 1/10th of a CF or .748 gallons (3/4 gallons).

If the clock hand movement is timed by a stop watch for just one digit, this can easily be converted to Gallons Per Minute.

As an example, if one digit was timed at one minute, the flow rate in gallons per minute would = .748 gallons per minute.

If one digit was timed at three minutes, the flow rate would be as .748 / 3 = .249 gallons per minute (about a quarter gallon per minute).

If when timing you have a remainder of seconds, always convert the seconds to a decimal value by dividing the seconds by 60. In this example the seconds were 30 however as converted to a decimal value it would be .5 minutes.
Here’s an example of a time measurement of one digit as 1 minute and 30 seconds (1.5 minutes). the math is as follows: .748 gallons divided by 1.5 minutes = .498 gallons per minute as a leak rate as measured at the meter.

If one digit is measured at 3 minutes the math is very easy as shown. .748 gallons divided by 3 = .249 gallons per minute (about 1/4 gallon per minute)

I hope you find this information helpful in quantifying a leak size on your home or business property. Please freely call me if you have questions OR need help locating a leak issue.

Michael Fend – 253.886.1400