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Unsplash/Autri Taheri

Bottled water isn’t cheap. At an average cost of $1.22 per gallon, we spend 300 times more on packaged H2O than we’d spend to drink it from the tap. In most cases, this expense is far from worth it, since both types of water are equally safe, taste identical, and in some cases even come from the same source.

There are some important exceptions, however. People living near private wells do not enjoy the same rigorous testing as those whose water comes from public sources. Some public sources are not properly screened, as was recently seen in Flint, Michigan.

A new report from the Natural Resources Defense Council suggests that the problem is much worse than researchers thought. It all comes down to testing — or in some cases, a failure to do so.

Typically, tap water is tested regularly for quality and contamination in accordance with laws from the Environmental Protection Agency (EPA). The main law involved here is the Safe Drinking Water Act, passed in 1974.

That act sets up a system of health-based standards that community water agencies must follow. Regular testing of the water supply tells experts when one of these standards isn’t being met. In its new report, the NRDC documents more than 80,000 violations of the law by community water systems in 2015 alone.

“Nearly 77 million people were served by more than 18,000 of these systems with violations in 2015,” the agency says in a press release. “These violations included exceeding health-based standards, failing to properly test water for contaminants, and failing to report contamination to state authorities or the public.”

As the report reveals, the quality of your tap can vary considerably based on where you live. According to EPA law, you should receive an annual drinking water quality report, or Consumer Confidence Report, by July 1 that details where your water comes from and what’s in it.

But in 2015, this law was violated nearly 8,000 times by community water systems serving more than 14 million people, according to the report. That could mean that the reports were not sent…