Erin Brockovich has claimed she has made a map of 10,000 communities across the US whose populations are suffering due to a polluted and contaminated water supply like in Flint, Michigan.

The real-life lawyer, who was played by actress Julia Roberts in a film about Ms Brockovich's fight for the residents of Hinkley, California to receive clean drinking water, has written a blog post for Medium which details how the disaster of polluted water is lying in wait to be exposed across the US.

She said she has been able to write a list of affected towns and areas because she receives “hundreds of emails” from worried citizens every day.

Her comments come the same week that Michigan Governor Rick Snyder testified in court about how much he knew and when he found out about the water crisis in Flint that affects 100,000 residents in his charge.

In the heated exchange between him and Republican Congressman Matt Cartwright, Mr Cartwright said: “[…] I’m not buying that you didn’t know about any of this until October 2015. You were not in a medically induced coma for a year and I've had about enough of your false contrition and your phony apologies.”

“Susan Hedman from the EPA bears not one tenth of the responsibility of the state of Michigan and your administration and she resigned," he added. "And there you are, dripping with guilt, but drawing your paycheck, hiring lawyers at the expense of the people, and doing your dead level best to spread accountability to others and not being accountable. It’s not appropriate."

When Ms Brockovich learnt about Flint, Michigan in Feruary 2015, her investigator Bob Bowcock was “on a plane the next day”.

“People have been drinking water that’s contaminated with PFOA or lead or TCE or other chemicals for too long,” she wrote. ”Towns in New Hampshire, Vermont, and New York are learning that their water is contaminated. Schools have turned off water fountains due to lead poisoning. Hannibal, Missouri and Tyler, Texas and Sebring, Ohio are all sounding the alarm."

Her post comes as reports are flooding in from Newark, New Jersey that authorities have started to test the levels of lead in the city’s water supply.

Ms Brockovich said the Environmental Protection Agency (EPA), charged with overseeing the Safe Drinking Water Act, is “over burdened, understaffed, and broke."

“We learned just this week that, in a memo, an EPA official stated that “Flint was not worth going out on a limb for.” The fact that someone from the governmental agency that is there to protect the health and the welfare of the people made such a disgusting comment will tell you where the problem is,” she said.

The 55-year-old lawyer and environmental activist has called for Michigan Governor Rick Snyder to step down, instead of spending “millions of dollars of tax payers’ money to defend himself”.

“Where is your decency? Where is your integrity as a human being, Governor? Please step down. Save that money, give it to those people who need it, get out of office, and let us begin the difficult task of repairing this problem,” she said.

Her blog has been published the same week that the Federal Emergency Management Agency denied Mr Snyder additional funding to deal with a crisis that has lasted over two years.