It's a chemical made famous by Erin Brockovich.
It's called hexavalent chromium or chromium 6.
It's a carcinogen and experts, like Millersville University Professor Ed Rajaseelan, say it can be found in drinking water.
"If they're regularly drinking this, regularly drinking really really high levels, it will cause cancer, mostly stomach cancer."
The Environmental Protection Agency has a drinking water chromium standard of 100 parts per billion.
Professor Rajaseelan breaks down what that means for you.
"If you drink 2 liters of water a day that has that much chromium in it, chromium 6 in it, after 70 years one in a million may get cancer."
Recently, the Environmental Working Group or EWG did a study on chromium in our drinking water.
It looked into drinking water studies in all 50 states.
Turns out, there are detectable chromium levels in every county in central Pennsylvania.
In California, the public health goal is .02 parts per billion for chromium in drinking water.
There is a lot more than that in our water.
According to those studies York County's average drinking water chromium level is at .193 ppb, Lancaster County is .172 ppb. and Dauphin County is .0784 ppb.
"That is very, very low," said Rajaseelan.
There's a catch to that study.
Rajaseelan says those levels included both chromium 3 and 6.
While chromium 6 could cause cancer, chromium 3 is an important nutrient in our diets.
Either way, there are ways to remove chromium from our water.
The best way, experts say, is also the most expensive and requires putting a metal iron like lead into the water which isn't ideal for the stuff you drink.
"So, the problem with purification during the normal system is that we can't add lead into water. So, trying to remove chromium 6, we're adding more toxic irons," said the Millersville University professor.
So, with the highest chromium level in our area in York County at .193 ppb, we asked Professor Rajaseelan if he feels safe drinking our water.
"I will trust it and drink it."