An increasing number of white-capped fire hydrants have dotted Salem streets in recent weeks, and it's clearly not because of snow.

Instead, it's the result of a process that so far has flagged about 60 of the city's roughly 900 hydrants as potentially deficient for firefighting. Before the inspection process is over, more white-capped hydrants may be added to the ranks.

Salem's Water and Sewer Department has been testing the city's hydrants and identified those that have low-flow capacity -- a potential problem for firefighters when it comes to fighting blazes.

But Salem officials say there is no need for alarm.

"None of our citizens are in danger of their houses burning down because of lack of water," Salem fire Chief Pat Counts said.

Identifying the low-flowing hydrants is one step in a process of assuring that firefighters have adequate water to put out fires.

After a hydrant has been judged low-flow and painted white, it is retested by Salem's Water and Sewer Department and may be upgraded and painted a different color or prioritized for repairs, Director Melvin Doughty said.

The color-coding system is not unique to Salem.

Salem, Roanoke, Roanoke County, Vinton and other jurisdictions nationwide follow recommendations of either the American Water Works Association or the National Fire Protection Association.

"We've painted and maintained our hydrants for a long time," said Sarah Baumgardner, environmental communications coordinator for the Western Virginia Water Authority, which works with Roanoke and Roanoke County.

Public hydrant barrels in Salem, Roanoke and Roanoke County are painted reflective silver. But the tops and nozzle caps of hydrants are painted different colors, and each color indicates a specific flow capacity.

Light blue indicates the highest capacity -- at least 1,500 gallons per minute. A red cap indicates low capacity -- less than 500 gallons per minute.

Although both the AWWA and the NFPA recommend every hydrant have a capacity of at least 500 gallons per minute, Counts said a hydrant with a pressure of 250 to 500 gallons per minute is sufficient to douse a typical house fire.

In Salem, all the hydrant tops and nozzle caps that normally would be red are being repainted white because that color is more visible after dark, Planning Director Melinda Payne said.

Of that group, some have a flow capacity of less than 250 gallons per minute.

Fire officials are carefully keeping a list of all hydrants with inadequate flow. Those will not be used in the meantime, Counts said.

The department has also developed a contingency on fighting fires near low-flow hydrants, Capt. John Prillaman said. When that happens, they'll know the location of the nearest hydrants with higher flow capacity.

"Maintaining fire protection is an ongoing problem," Doughty said.

A couple of factors can cause low-flow hydrants. In some cases, it's because aging, unlined pipes that serve a hydrant have developed deposits that inhibit water flow, Doughty said.

In other instances, it's because old 2- or 4-inch-diameter water lines serve a hydrant, Counts said. Such pipes are often too small to provide adequate water. The minimum diameter of newly installed lines to hydrants is 6 inches.

Flow can sometimes be restored by flushing water lines to remove deposits. But when water lines to hydrants are very narrow, they need to be replaced with wider ones.

One reason Salem is retesting all hydrants is because of a 2006 fire in Vinton that resulted in heavy damage to a family's house, Payne said.

In October 2006, Vinton volunteer firefighters were unable to get sufficient water flow from a town-managed hydrant while responding to a fire in a Roanoke County subdivision.

At that time, Town Manager Kevin Boggess said a new hydrant was installed within a week and that firefighters later demonstrated its functioning in an effort to ease residents' concerns.

Boggess will become Salem's city manager in February.

Information about the Salem hydrants will be included in a city magazine distributed by the end of the year, Payne said.