Fracking leaks methanol, salts and other compounds into ground water. Operations often contaminate water from leaky pits with diesel and other compounds.
Coal is probably the nastiest fuel by any measure. But that isn’t to say that fracking operations are not problematic, and since industry has fought tooth and nail to prevent meaningful, peer reviewed study of the issue, it’s absurd to compare to a well understood, well measured thing like air safety.
No, the evidence from peer reviewed studies show that this does not occur often. You are presenting this as though fracking leads to ground water contamination. That is simply not the case. Agriculture and urban activities are much bigger sources of contamination.
This recent review says: “ A perceived risk, that fracking chemicals may migrate from the 0.5- to 3-km depth of injection to upper shallow aquifers used for water supply, is not considered to be significant (90, 91). The lack of baseline data on aquifer conditions is cited as a major limitation to the detection and attribution of the impacts (90–92). Wide variations in methane concentrations in groundwater are noted in areas with intensive gas production as well as in areas with limited activity.” https://www.annualreviews.org/doi/full/10.1146/annurev-envir...
Hammond, P. A., Wen, T., Brantley, S. L., & Engelder, T. (2020). Gas well integrity and methane migration: evaluation of published evidence during shale-gas development in the USA. Hydrogeology Journal, 28(4), 1481-1502.
There are better criticisms of fracking like the higher rates of disease around well sites, and improper dumping of waste.
Contrast this to the evidence for coal contaminating water supplies with mercury. Fracking, despite its reputation and scary name, is safe. Like, flying airplanes safe.