Why are Knoxville fire hydrants blue and yellow? | Know Your Knox

Keen-eyed Knoxville residents have noticed a small yet curious difference between the Scruffy City and the rest of America. Instead of the traditional red, almost all the city's fire hydrants are blue and yellow.

So how exactly did Knoxville end up with this paint job that doesn't seem to be replicated in other parts of the country? And perhaps most important of all, if hydrants are going to be another color, why don't they reflect University of Tennessee pride in orange and white?

The origin story of the blue and yellow hydrants involves some serious technical identifiers, and at least a little more intrigue than you might expect for a ubiquitous part of city life.

Why are Knoxville hydrants blue and yellow?

Let's start with the mechanics. There are two parts of a fire hydrant: the "bonnet," which sits on top, and the "barrel," which is the body that comes up from the ground. The bonnet is color-coded in alignment with National Fire Protection Association standards, the Knoxville Utilities Board said in an email.

Bonnet color coding alerts firefighters to the hydrant's "flow potential," or how many gallons of water can be released per minute. The color blue, which seems most common in Knoxville, indicates the highest flow potential.

But once you start looking, you'll notice there are additional color combinations around town, too. Other bonnet colors in the system are green, orange and red, indicating flow potential in descending order.

There's actually a formula firefighters use to know how much water is needed for a fire, Knoxville Fire Department spokesperson Mark Wilbanks said, so it's important that crews can quickly identify the flow potential and calculate if it will be adequate.

Hydrants with red bonnets are the least useful and are typically only tapped when there aren't other options, Wilbanks said.

Knoxville hydrants with yellow barrels use water from KUB's public utility system, according to an email from KUB. Approximately 8,500 hydrants around town fall into this category.

The National Fire Protection Association color guidelines are designed to help crews at a quick glance, but ultimately it's up to the municipality or utility to decide what colors to paint hydrants.

Could Knoxville's fire hydrants get a makeover?

Some cities have fire hydrants that aren't subject to the rules and regulations we've outlined here.

Lantana, Florida's Adopt-A-Fire Hydrant program produced a Minion hydrant there, while the Art on Fire project in Geneva, Illinois, resulted in a Disney character Mike Wazowski hydrant. The round "outlet" on each hydrant is particularly conducive to depicting one-eyed creatures.

Meanwhile Somerset, Kentucky, touts hydrants decked out for the University of Kentucky with a barrel in UK blue.

So why can't Knoxville do the same?

"KUB has worked with community partners on beautification projects over the years, but not specifically for fire hydrants, as the visible colors are important to maintain," KUB said in the email.

Besides stripping away vital info from firefighters, cute paint jobs can create problems.

"That’s not a good idea," Wilbanks said. Critical parts of the hydrant could unintentionally be painted shut in the makeover, he said, and maintaining the visual code is important when time is of the essence.

Know Your Knox answers your burning questions about life in Knoxville. Want your question answered? Email [email protected].

Hayden Dunbar is the storyteller reporter. Email [email protected].

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This article originally appeared on Knoxville News Sentinel: Why are Knoxville fire hydrants blue and yellow? | Know Your Knox