SMITHFIELD — In April, Smithfield learned it has the best-tasting water in Virginia. But it has since learned the water might include too much of a good thing – fluoride.

Fluoride, a naturally occurring salt-like substance in the water, helps prevent tooth decay. While some localities add it to their water, water in Isle of Wight and parts of Suffolk contains so much fluoride that it can stain teeth brown.

For the first time in more than 15 years, Smithfield’s fluoride level has exceeded the maximum federal level and might require the town to take expensive steps to reduce it.

“We’ve been very fortunate for years,” said Town Manager Peter Stephenson. “We’ve been knocking on a lot of wood and finally ran out of luck.”

Fluoride is measured in parts per million. The national fluoride standard, established about 20 years ago by the Environmental Protection Agency, is 4 parts per million. A regular tube of toothpaste contains about 100[0] parts per million of fluoride.

When two Smithfield wells – on Church and Jefferson Street – repeatedly tested between 4.07 to 4.54 last week, the town had to inform the Drinking Water division of the Virginia Department of Health in Virginia Beach.

If confirmation tests come back with results 4.05 or higher, the town will have to either build new wells or install expensive filtering systems, costing in the hundred thousands of dollars.

Localities are required to test their fluoride levels every three years. Once these levels exceed the 4.0 mark, quarterly re-tests are mandatory.

The Department of Health monitors fluoride levels two ways:

If the fluoride level is below 2.0 parts per million, it’s called the secondary standard. Above this level, it’s highly likely that young children – until their permanent teeth come in – will develop off-white to brownish discolored or pitted teeth, said Dan Horne from the Health Department.

All of Isle of Wight’s water systems exceed the 2.0 mark.

If the fluoride level exceeds 4.0, the so-called primary contamination level, localities are forced to treat their water to reduce the fluoride level.

“This is the level where EPA said you can see health effects,” Horne said.

These health effects include increased discoloration of teeth and risk of skeleton fluorosis, a disease that makes bones brittle and affects primarily older people, said Rick Rogers, Chief of Drinking Water for the Environmental Protection Agency.

So far, the Virginia Health Department has not identified a single case of skeletal fluorosis.

Cities like Newport News and Williamsburg that depend on surface water – rivers, lakes and reservoirs – have a lower level of fluoride than counties such as Isle of Wight, which draws its water from ground wells and springs.

Newport News, whose water systems serve Hampton, Poquoson and part of York and James City counties, adds fluoride. This brings these water systems up to a so-called optimum level of 0.9 – the ideal level of tooth protection. Fluoride levels below 0.7 can cause tooth decay and cavities.

In Isle of Wight, three of six wells – at the Obrey subdivision, Smithfield Heights and Carrsville — tested between 5.2 to 5.4 parts per million.

In Battery Park, the fluoride level exceeded 6.1 parts per million, forcing the county to close this well and buy water from Smithfield for the area.

But high flouride levels aren’t a secret in Isle of Wight

“We always knew about it,” said Smithfield resident Kristin Wilda.

The Wildas raise five children. They buy bottled water and use town water only for brushing teeth and cooking.

“We are probably not as careful as we should be, ” Wilda said. “But so far, our kids are ok.”

Dr. Wilson Ames, a third-generation local Smithfield dentist, knows of residents in particular coming from Rescue and the Battery Park area complaining about brownish teeth stains.

“We see now less than when we started 40 years ago,” Dr. Ames said.

Smithfield realtors tell their clients – in particular those with small children — about the county’s high fluoride level.

“It’s not a big deal,” said John Graham of William Wood and Associates. “I tell them that there has been some concern regarding city water and children’s teeth and they should check with the town and the dentist.”

Isle of Wight will spend about $1.3 million in the next five years for test-drilling wells to find better water, starting this fall, said Isle of Wight’s Utilities Director Wayne Roundtree.

“The state didn’t give us a choice,” said Board of Supervisors Chairman Richard MacManus.

Windsor also received bad news this spring. Its well on Duke Street tested 4.05. But Windsor has already built a new well.

The new well, costing the town approximately $330,000, received a clean fluoride bill of health and will be ready for service by the end of this year, said Town Manager Kurt Faulkenstein.

Sabine C. Hirschauer can be reached at 247-4536 or by e-mail at shirschauer@dailypress.com