DALLAS (CBS11 I-TEAM) – In North Texas, there is a one in four chance the tap water is either unsafe to drink or has not been properly tested, according to a CBS11 I-Team investigation.

The I-Team examined the 76 largest water utilities in North Texas and found 20 to be in violation of the federal Safe Drinking Water Act. These 20 water utilities with violations provide water for more than 1.7 million people.

The violations range from having too much contamination in the water to not doing enough testing.

In many communities, residents are often unaware of the problems.

“We assume that the water coming into our homes through our city is clean,” White Settlement resident Rachel Rogers said.

According the federal records, White Settlement, a city west of Fort Worth, has had more than 78 violations of the Safe Drinking Water Act since 2014.

In the letter sent to residents last month, the City of White Settlement acknowledged “elevated levels of lead in the drinking water” were discovered after samples were taken in December.

The letter warns lead in water can cause “serious health problems” including damage to the brain and kidneys and has been linked with “lowered IQ in children.”

This is not the first time residents in White Settlement have been warned about their drinking water.

In 2014, levels of radioactive contaminants were discovered in the water that exceeded maximum federal limits. The EPA warns these type of chemical elements can lead to an increased risk of cancer.

According to federal records, it took the city more than three years to fully resolve its radioactive contamination violation.

Water quality experts said maybe even more concerning is what White Settlement residents don’t know.

Before testing the water for lead and copper in December, the I-Team discovered White Settlement had gone five years without doing any lead or copper tests.

During this time, the city was required by federal law to test every couple of weeks.

That means out of the 180 tests the city was required to do during this time, it did none.

The I-Team found in the past two years the North Texas city also failed to monitor its water for nitrate, metals, synthetic organics, volatile organics, E-coli, as well as other potentially dangerous containments.

“They haven’t been doing what they are supposed to be doing for the past few years and I’ve been here for five years drinking this water every day,” White Settlement resident Ann Mills said. “Potentially, that’s what keeping some of my health issues ongoing.”

White Settlement Mayor Ronald White said until recently he had been unaware that the water was not being tested for lead or copper.

“I want to know how it happen, why it happened, and who’s responsible,” said White, who has been in office since 2014.

White said the city’s public works director in charge of testing the water was fired, but Robert Smith told the I-Team he resigned in October for reasons unrelated to the water issue.

Smith said he does not remember if all lead and copper tests were done.

When the I-Team asked White if he felt responsible for the water violations, he said, “I can only know if it was reported to me.”

White said the city is in the process of testing its water and is taking steps to comply with federal standards.

White Settlement is also offering to test any resident’s water for free.

Despite the problems, White said he believes the water in his town is safe.

“I don’t feel like there’s a problem with our water,” White said. “The only thing I can say is I haven’t gotten sick. I don’t know anyone from the city that has gotten sick from the water.”

Water quality expert and consultant Bob Bowcock said city water departments that cannot follow simple federal water testing rules often have trouble with keeping the water clean.

“If they can’t engage themselves in the most basic activity of doing a very simple monitoring program, it’s an indicator that the entire system is failing,” Bowcock said. “I would be very concerned because you really don’t have a good idea of what’s going on.”

Despite these concerns, the federal government rarely penalizes violators. Most of the time enforcement is left up to the states. In Texas, the Texas Commission on Environmental Quality handles most enforcement actions.

After years of not testing for lead and copper and after ignoring four written violation notices, in February TCEQ issued White Settlement a rare financial penalty totaling $1,950.

Click here for a list of contaminants in your water.