Cullen Hoback had been in West Virginia for some time, exploring the situation in Charleston where the water supply had become contaminated by a detergent for coal called MCHM, when someone slipped him an invitation to a most curious event, the Berkeley Springs International Water Tasting on the other side of the state. It was less than 24 hours notice, but Hoback dropped everything and jumped in the car.

“Just the idea of a bunch of people sitting around and judging which water is the best happening in the same state where water is some of the worst in the country – that juxtaposition was just too much to pass up,” says Hoback, who can be seen in his latest film, “What Lies Upstream,” bringing a water sample from Charleston to be judged by the international panel of judges. “In a movie that had a lot of very serious things happening, it’s a nice moment of levity and it also gave me a chance to demonstrate just how bad the water smelled, because smell is a hard thing to translate visually. The only way to do that was having German drinking water judges who craft their own water react to this liquorice-smelling monstrosity.”

Still, had it not been for the smell of the water, no one in Charleston may have know they were being poisoned there until their health problems set in, and if it wasn’t for Hoback’s dogged investigation, which grew out of personal curiosity into a professional crusade, few outside of Charleston would ever care to remember the time when residents were grasping for soda and bags of ice to melt down at their local supermarkets to have something to drink after the shelves had long been cleared of fresh drinking water. However, one suspects with “What Lies Upstream,” which premieres tonight as the opening night film at the Slamdance Film Festival, the disgrace of what happened in West Virginia and since has plagued Flint, Michigan and other cities we may not even know about yet, won’t be so easily swept under the rug.

Hoback, who previously made the cheeky yet enlightening “Terms and Conditions May Apply,” about the user agreements which so many of us sign before reading the fine print, once again finds a compelling way to connect the dots between a consumer experience we all can identify with and a tangle of profit-driven corporations and lack of government oversight that we can’t possibly fathom. Discovering a substance in the Charleston water supply that once made lab rats pee in red — and green — the filmmaker makes himself a fly on the wall at community functions and even private lobbying meetings to learn how the response to the dirty water is being shaped. But it’s in traversing the state to talk to government officials — going fishing with the state’s Department of Environmental Protection Randy Huffman and playing around with the son of State Senator Chris Walters, whose delayed muscle development raises red flags — that Hoback shows a real gift at bringing out the human side of how political decisions are made, observing how the dependence on jobs in the coal industry has quieted conversation on both sides of the aisle about public health concerns and how mechanisms for information dissemination are hardly dependable.

There’s a rigor to Hoback’s inquiry that sets “What Lies Upstream” apart from most advocacy documentaries, though it’s also how the film conveys its findings about a relatively arcane subject in such an accessible way that makes it as engaging as it is disturbing. On the eve of the film’s premiere, Hoback spoke about not drinking the Kool-Aid in West Virginia and how he gradually educated himself to become a water expert, as well as the importance of keeping the camera rolling on a documentary.

How did this come about?

It all started with a text from my mom. She said, “Did you see what’s happening in West Virginia?” I had family in West Virginia growing up — we’d visit my uncle there, and he’s passed away since, but I checked the news and, sure enough, you have 300,000 people without drinking water. It seemed to me like the real mystery of why that crisis had happened wasn’t being solved by the media. I have a little bit of an investigative funny bone in me, so I was like, “Well, maybe I can figure out why this happened.” Initially, I was there just to get to the bottom of it, [with] my emotional ties mixed with some curiosity, but the story evolved a ton after that, [leading] to asking much bigger questions about what’s wrong with the drinking water system in America.

This both seems like an extension of your work in “Terms and Conditions May Apply” in its zeal as a consumer advocacy story, but also in stark contrast to it because it’s a far more cinematic subject than paperwork. How much could you draw on what you learned on the first one?

Like a lot of documentaries, I think “Terms and Conditions” was a bit of a retrospective. I did a confrontation with Mark Zuckerberg and there were some things happening in real time, but a lot of it was looking back on how we got to where we were and what it was going to mean for the future. What was so cool about this new film and my hope for it was that we would be able to capture all of this in real time. Rather than having to have interviews take us back to what happened, we would be there for it and of course, that means you don’t know if the story is going to be something worth investigating or not. But I wanted to make something more cinematic, and this story, that takes place in the physical world with real characters, gives you more of an opportunity to tackle something in a way that feels more like a narrative. Structurally and visually, I wanted it to feel like you’re almost watching a fictional film, except everything’s real.

I was surprised with how accessible everyone seemed to be. You’re actually going fishing with Randy Huffman, West Virginia’s Department of Environmental Protection Secretary, and invited into the home of West Virginia Department of Health and Human Resources’s state health officer Dr. Rahul Gupta, both of whom are viewed skeptically at one point or another during the film. Were people open to talking?

Again, this is something I never would have predicted. The water crisis that happened there really opened people up in a place that, generally speaking, has an aversion to outsiders, and definitely to cameras. In a very real way, folks who work in either the chemical or coal industries see any kind of publicity that might come out about their work as things that might take away jobs. Historically, it’s an impenetrable place, but they wanted to talk about their water and how [the crisis] had impacted them. Of course, you have all of the people who are the victims, but I was more interested in the people who might be more responsible for this and the politicians who are theoretically trying to do something about it.

In those early stages, it was much easier to get access because people wanted to talk. Everyone wanted to play the role of the hero. As I think Rahm Emanuel said, and a few others before him, “Crisis is too good of an opportunity to waste.” Everyone was eager to show how capable they were of tackling this problem. What I don’t think anyone expected, including myself, was that I was going to stick around for another couple of years and follow the story after all of the press and media attention went away. That’s when everything really heats up, because when the politicians and the regulators are no longer in the spotlight and they can behave like no one’s watching. But once they’d already given me that initial access, I think it was very difficult for them to say no to me, because they knew they were part of this project and perhaps they were concerned of how it would look or they wanted to see it through. I just got there at the right time.

It seemed like some of the most valuable interviews came from candid chatter you’d catch from afar or just after a more formal interview ended. Was just a simple instruction to your camera guys to keep rolling or something more devised?

I always told my cameraman or anyone I worked with, “The interview happens after the interview.” You film the interview, then everyone feels like it’s done. Maybe they hand you back your mic. But you just keep rolling. It gives everyone permission to think, “Well, maybe this isn’t actually part of the film. Maybe it is.” Those are the moments where everyone is usually more willing to speak freely and they make for the best moments in the film because they’re the most candid. There was some stuff that we had to film in a [more] secretive way, like the secret meeting of the lobbyists I walk into. We had a gigantic camera, so they knew we were there, but a lot of this stuff you’ve just got to get on the first take. You hope that your audio and everything else is going to work, because it’s not like I can confront a senator in the hall of the Senate more than once.

Was there a point where you had an idea of what this might be and then it changed direction in a way you didn’t expect?

Yeah, I was really struggling for a long time with the movie, because I’d spent all this time in West Virginia and I wasn’t sure if maybe it was just a West Virginia problem [because] the socio-political system there was unique. Flint really opened up the story and helped me see the bigger picture. It wasn’t the event [of the Flint water crisis] as much as it was the person who actually revealed that whole event, Dr. Edwards and the conversation that we have – it’s not in the film because it would be ridiculous for me to ask him this question five times -‎ but I had a very hard time wrapping my head around the idea that the EPA weren’t the good guys. They were, in fact, covering up contaminations, doing these things to protect their reputations, and this trend wasn’t just at the federal level. It was happening around the country and the problems with our regulators aren’t just because politicians are putting lobbyists in charge of the organizations, but [there’s this] trickle-down effect influencing how scientists behave. As time goes by, the scientists want to protect their jobs and that leads to coverups and to fictionalized science so that they can keep their jobs.

The irony of that was really hard to wrap my head around. You’re going to keep your job by not doing your job? As long as people believe that the system is protecting them, I guess that’s what has been the status quo for a long time. That just totally blew my mind. I wasn’t expecting [Dr. Mark Edwards, a professor at Virginia Tech] to say that at all and it completely shifted the trajectory of the film as well as the focus. I turned [the focus] back more to key regulators who I had this incredible access to in West Virginia, as well as the EPA and, particularly, the CDC who were doing suspicious things related to that chemical that spilled.

You eventually start doing water tests on your own‎ – is that even the kind of thing you can budget for when you start making this film?

This is part of the research into this film. I had to learn all the terminology. I had to understand a lot of the science behind how these things work so I could figure out how to ask the right questions and talk to scientists on a level where they couldn’t just brush me off because I didn’t know enough of the technical terms. That helped me a lot. I also had to learn this stuff so that we could conduct our own testing and I could understand what the outcomes of that testing meant. My journey in the film really is my journey and I think the audience goes with me, learning how to do these things along the way.

Testing my own water is expensive, and that’s part of why I didn’t want to have to do it. It’s part of why it’s not done [in general]. The other reason why it’s not done is because, in a lot of ways, people don’t want to know what’s in their water, or at least that’s the assumption. I think people do, generally speaking, want to know if something is wrong or harming them or their children. It’s a shame that our politicians and our regulators don’t look for things that they don’t want to find.

Since the situation is still unfolding, was it a difficult call to stop filming when you did?

This time it was pretty clear, just because the [narrative] arcs were there for my main characters. I wasn’t sure I was ever going to figure the story out, but once I did, it was easier to put a timeline on it. Obviously, with anything like where you have events happening in real time, you can follow people until they die. But [with] the Trump election, which I never saw coming, that’s the button on it. Suddenly, the film wasn’t just, “Oh, look at what’s happening in West Virginia.” It was, “This is actually what’s happening across America.” What I had just documented in West Virginia was now the mentality that was going to be playing itself out across the entire country. The very same things that led to this contamination are the same kind of misguided ideologies that are being implemented nationally. Seeing that happen gave the film this whole new relevance and there was a real urgency to get the film out there.

It’s early days, but I remember with “Terms and Conditions” there was a larger campaign going on around that film. Do you have such plans for this one?

We do. We haven’t nailed them all down. But part of what need to happen is to do more independent testing, because we can’t trust the regulators. We can only really trust ourselves and good scientists who are actually responsible and want to get things right. I’d love to mount a campaign related to doing more independent water testing across the country and tries to separate politics from science so that politicians aren’t determining what flavor of science we’re going to get, whether or not we’re going to continue to investigate climate change. These should be decisions made by scientists, not by politicians. When scientists become beholden to political agendas, you can expect the science coming out of those agencies to be crummy.

“What Lies Upstream” does not yet have U.S. distribution. It will play at the Slamdance Film Festival on January 20th at 6:45 pm and January 23rd at 3 pm.