Listen to today's Environment Report.

Tomorrow evening at 7pm, the Michigan Department of Environmental Quality is holding a public hearing on a request from Nestle Waters.

The company wants to increase the amount of groundwater it pumps to 400 gallons per minute.

The state says 49 companies bottle water in Michigan.

We've been working for months to find out how much water those companies bottle and sell. But finding accurate information has been difficult for a few reasons.

First, most companies aren’t required to report how much they bottle.

In Michigan, if you pump water out of the ground, and you have the capacity to pump 70 gallons per minute or more, you have to report how much you withdraw each year to the DEQ. But if you bottle tap water, or if your pumping capacity is less than 70 gallons per minute, you don’t have to report how much you use.

Many Michigan bottlers are small scale, and many aren't operating the same way as Nestle (think the people who deliver five gallon jugs to your office). A few facilities are simply places where water is processed and people come in and fill their own bottles.

However, there are also operations owned by large corporations that don't have to report. For example, Coke and Pepsi process and bottle Detroit city water under the brands Dasani and Aquafina, and because it's tap water, they don't need to disclose the amount.

We contacted every facility that doesn't have to report, and only 10 of them released information on their water sale volume. Four said they actually don’t keep track.

On top of all this, it was hard to even put together an accurate list of bottlers and their sources. The state’s data can be a little confusing, and there are a few inconsistencies.

We discovered several facilities that the state wasn't tracking.

If you want to bottle water in Michigan, two state agencies are involved. You have to get the DEQ to approve your water source, and you have to register with the Michigan Department of Agriculture and Rural Development each year.

In the course of our research, we found two facilities that were bottling water but were not properly registered with the state. After we notified MDARD about these facilities, a spokesperson said they’re currently bringing those companies into compliance.

The DEQ had also completely missed a facility that was supposed to be reporting how much water it uses.

Andrew LeBaron is with the DEQ's water use program. He says that this company, Besco Water Treatment, has been out of compliance for the last 10 years.

“They were not aware of the regulation in the first place. It’s a somewhat recent change in the law based on an amendment to the law, that would require them to begin reporting. It’s been about 10 or 11 years now that it's been in place, but their wells pre-dated that law,” he says.

LeBaron says he doesn’t expect the DEQ to fine the company in this case.

"In a case like this, it's certainly not our intention to pursue penalties or fines for them not being aware of the water use reporting requirement, and they were very cooperative from this point forward, to begin that," he says.

Besco has not responded to our request for comment.

Selling water outside of the Great Lakes

There are rules under the Great Lakes Compact about how much water can get taken out of the Great Lakes basin. But there’s an exception for bottled water.

Water can leave the basin in containers of 5.7 gallons or less. This allows bottled water and other beverage companies to ship their products outside of the basin.

It’s important to note that reported bottled water withdrawals make up a very small percentage of water use in Michigan - around 1/100th of a percent. But, we don’t know how much water is bottled and not reported.

Liz Kirkwood is the executive director of the environmental group, For Love of Water. She calls the lack of reporting on bottled water “troubling.”

“The state should know absolutely with 100% certainty where every single gallon is going, and they should track it,” she says.

See our attempt to track bottled water in Michigan below:

Mark Brush and Rebecca Williams contributed to this story.