ST. PETERSBURG— The city is losing water.
On an average day, the city buys more than four million gallons from the region's water supplier than it sells to residents and businesses, according to an audit earlier this month. That costs the city — and its customers — $3.4 million annually.
Some of the water goes to clean city pipes by flushing them. However, much of it is used by customers but fails to register on what the city acknowledges are thousands of faulty residential meters.
The rest? The city isn't sure where it goes.
"There is no way to estimate what we don't know is broken," said Public Works spokesman Bill Logan.
The city is not alone. But it has greater trouble accounting for where its water flows that most other local suppliers, according to the audit by the Southwest Florida Water Management District, the agency commonly known as Swiftmud.
And the problem is getting worse.
From 2001 until 2010, the city lost anywhere from 2.6 percent to 4.9 percent of its water supply daily. During the last two years, the city reporting losing 16.7 and 15 percent respectively of the water it buys from regional supplier Tampa Bay Water daily.
Those percentages are greater than all but 24 of the 140 utilities monitored by Swiftmud, which oversees the region's water supply. They also surpass the agency's standards, which is what prompted the audit.
It blamed faulty residential meters and pipe flushing as the main culprits, accounting for an estimated 79 percent of the loss.
But city officials won't know for sure until they can inspect the pipes more closely. And they couldn't explain the sudden surge in water loss.
"I cannot provide you with an exact explanation of what transpired and do not want to make assumptions," Logan wrote in an email that listed 13 possible contributing factors from clerical billing errors to hot temperatures.
City Council member Karl Nurse, a Tampa Bay Water board member, said one reason might be that the quality of water from the regional water body has declined in recent years, partially because of the drought that lasted into the spring. More dissolved plant material increases the need to flush the lines, he said.
Tampa Bay Water officials have said utilities around the region have been having to flush more often, he said.
Still, Nurse wants a solution. "We need to get this fixed," he said.
TAMPA BAY TIMES COVERAGE: ST. PETERSBURG SEWAGE WOES
Some of that $3.4 million is just the price of maintaining high-quality water. If lines aren't flushed, dangerous bacteria can build up. A certain amount of line flushing is done in every system.
A possible partial solution to the city's water loss would be to switch to a disinfectant process that involves cleaning the pipes with chlorine twice a year, not unlike cleaning a swimming pool.
If the city did that, it would cut costs by about $700,000 a year by saving about one million gallons of lost water per day, said John Palenchar, the city's interim Water Resources director.
The downside? Changes in color, taste and odor for several weeks after each cleaning. Also, some environmental activists have charged that chlorine raises the level of dangerous cancer-causing by-products. Water officials say it doesn't endanger the public.
In St. Petersburg, an internal debate has been raging about whether or not to switch to chlorine, which is used in Pinellas County, Clearwater and Tampa, all of which have lower rates of water loss than the Sunshine City.
Waunda Barcus, the city's water treatment and distribution manager, favors making the switch, saying it would save water and be a more effective way to ensure proper disinfectant levels.
"I've suggested that since I've started here," said Barcus, who joined the city in December 2015. "Upper management has been totally against it."
Pinellas County water supply manager Steve Soltau said since the county switched to using chlorine to clean pipes in 2004, its has saved roughly 50 percent of the water it had used to flush them.
Residents complained at first, Soltau said, but a public education campaign has drastically reduced complaints, which now average about 40 per month.
The final call belongs to Mayor Rick Kriseman, who says city residents have been clear that they don't want to have chlorine pumped through their water pipes.
"At this point, that's the choice we've made — we don't want to put more chemicals in our water than you have to, which also might change the taste of the water," the mayor said. "Potentially, it would really change the taste and impact significantly more than flushing."
Meanwhile, St. Petersburg continues to lose water.
Fixing bad meters would help. Since identifying a design flaw in 50,000 water meters in 2014, the city has replaced about 20,000 of them, Logan said.
Yet, over that same time frame, the city's water loss rates has continued to climb.
Kriseman said he wants the city to demand compensation from the manufacturer. If that fails, the city may pursue legal action, he said.
And the city is looking to increase the ways it can recapture water used to flush the lines, perhaps by expanding pilot programs to use that water to irrigate city parks and other public places, the mayor said.
The city's water plant is in Odessa, 25 miles north of the city. Water takes up to two weeks to flow from the plant to the southernmost neighborhoods in the city. The long distance makes it harder to keep disinfectant levels where they need to be.
In the past, Kriseman said, he heard complaints about water quality from residents in those southern neighborhoods. One reason the city uses so much water to flush the lines, the mayor said, is to keep the quality levels high for those residents.
Despite the high price tag of losing so much water, he said there are no plans to change course.
"You always reevaluate," Kriseman said, "but our No. 1 primary intention continues to be the quality of water that we provide."
Contact Charlie Frago at email@example.com or (727)893-8459. Follow@CharlieFrago.