Fresh from gifting an unwanted “kid size” submarine to Thai rescuers working to free children trapped in a cave, billionaire entrepreneur Elon Musk has turned his attention closer to home – helping the city of Flint get clean water.

In response to a tweet requesting help for the Michigan city of Flint, Musk wrote that he will “fund fixing the water in any house in Flint that has water contamination above FDA levels. No kidding.”

Karen Weaver, the mayor of Flint, subsequently contacted Musk, co-founder of the electric car firm Tesla, on Twitter to talk about Flint’s “specific needs”. Musk has tweeted that he will speak to Weaver on Friday.

Mari Copeny, a leading Flint activist, tweeted on Thursday that she had been working with Musk’s team “for over a week” to find out the best solution for the city.

It is the Environmental Protection Agency (EPA) that sets lead safety levels for drinking water utilities, although the Food and Drug Administration (FDA) advises there is no safe amount of lead once it gets into the bloodstream.

Flint’s 100,000 residents were exposed to lead leaching from old pipes after the city switched water supplies in 2014 without adding corrosion-control chemicals.

The lead contamination, which has likely hindered the development of children and triggered an outbreak of legionnaire’s disease that killed a dozen people, caused international uproar and has resulted in criminal trials for several city and state officials.

Flint is in the process of replacing all of its old lead water pipes, a task the city estimates will cost about $55m. Residents have been provided with water filters and, until April, were also given free bottled water.

State officials have said that Flint’s water is now safe to drink, although this assurance has been met with deep skepticism among many residents.