I've Been Drinking Rainwater the Past 2 Years. Is It Time To Stop?

Recent studies find all rainwater may be unsafe to drink, according to the latest health advisories for levels of PFAS, also known as "forever chemicals."

Eric Mack Contributing Editor
Eric Mack has been a CNET contributor since 2011. Eric and his family live 100% energy and water independent on his off-grid compound in the New Mexico desert. Eric uses his passion for writing about energy, renewables, science and climate to bring educational content to life on topics around the solar panel and deregulated energy industries. Eric helps consumers by demystifying solar, battery, renewable energy, energy choice concepts, and also reviews solar installers. Previously, Eric covered space, science, climate change and all things futuristic. His encrypted email for tips is ericcmack@protonmail.com.
Expertise Solar, solar storage, space, science, climate change, deregulated energy, DIY solar panels, DIY off-grid life projects. CNET's "Living off the Grid" series. https://www.cnet.com/feature/home/energy-and-utilities/living-off-the-grid/ Credentials
  • Finalist for the Nesta Tipping Point prize and a degree in broadcast journalism from the University of Missouri-Columbia.
Eric Mack
6 min read

Was the rainbow reflected through rain too toxic to drink?

Johanna DeBiase

We're almost two months into the monsoon season in the US Southwest, and in that time well over 2,000 gallons of rainwater has fallen onto the roof of my small off-grid home, where it's been caught and diverted into two large tanks in my backyard. This water is pumped through a filter and into the house to be used for everything from laundry to drinking, but lately a rash of headlines have been shouting at me that my water is filled with "forever chemicals," making it unsafe to consume.

So do I need to go back to hauling our water from a community well five miles down the road, 200 gallons at a time, to be safe?

Although new interim guidelines from the US Environmental Protection Agency would seem to judge all rain on Earth unsafe to drink, I'm not ripping down the gutters and piping I just finished installing a few months ago. At least not yet. 

All this concern about tainted rain is tied to something called PFAS (perfluoroalkyl and polyfluoroalkyl substances) that comes from chemicals used in firefighting, industrial sources, landfills, wastewater treatment, and even shampoos and packaging. Some studies have shown potential links between PFAS exposure and decreased fertility, developmental issues in children, increased risk of some cancers and reduced immune system function.  

These manufactured substances are very slow to break down, likely making them ubiquitous in our environment, including in groundwater that evaporates and floats above our heads, where it travels on the wind and atmospheric currents before eventually returning to the surface as rainwater. A minuscule percentage of that rainwater falls onto my roof in New Mexico, runs through a series of gutters, hoses, screens, filters, tanks, pumps and other plumbing before coming out of a handful of kitchen or bathroom spigots in the house. 

You'd think rain falling on a relatively isolated high-desert locale surrounded by public lands would be in a pretty pristine state, but in a world where microplastics turn up in the Arctic and the bigger bits form a miniature floating continent in the Pacific, I'm beginning to wonder if pristine is going extinct. 

Setting my rain catchment system up was part of my most epic pandemic project, the unfinished, off-grid home my family moved into in April 2020. It was only in the past few months that I added the last lengths of gutter to the roof of our backyard storage shed to feel confident I was maximizing our rain catchment potential. 

Drinking water direct from the sky.

Johanna DeBiase

And then this month, the headlines began screaming at me that I was poisoning my family in doing so. And this isn't another case of tabloid or clickbait headlines exaggerating or taking things out of context. The sweeping conclusion is coming from the mouths of scientists themselves. 

"Based on the latest US guidelines for PFOA [one particular kind of PFAS] in drinking water, rainwater everywhere would be judged unsafe to drink," Ian T. Cousins, a professor of environmental science at Stockholm University, said in a statement.

Cousins is lead author of a study published Aug. 2 in the journal Environmental Science and Technology that declares a "planetary boundary" for PFAS contamination of our environment has been exceeded. 

Unlike other pressing environmental issues, however, what has changed in how we view PFAS contamination isn't necessarily the level of it in the environment. One of the biggest producers of the substances, 3M, stopped making them decades ago, and the amount of PFAS in our environment has actually been relatively stable during that time period.

What is different today are the standards for acceptable amounts of PFAS in the environment that regulators and health officials have decided we should aim for. 

"There is heightened concern regarding ingestion/inhalation of PFAS due to the very low threshold limit that can cause adverse human health impacts," Sudarshan Kurwadkar, an environmental engineer and professor at California State University, Fullerton, told me. 

That concern led the EPA in June to introduce new drinking water health advisories for PFAS. The guidance sets the target concentration levels for PFAS in drinking water so low as to possibly exceed the capabilities of current testing and monitoring technology. 

"From the perspective of a chemist, the new levels will be challenging to evaluate," Jennifer A. Faust, a chemistry professor at the College of Wooster, said via email. "For PFOA (C8), the new advisory level is 4 pg/L (picograms per liter), but the EPA's own method for analyzing PFOA in drinking water cannot confidently detect anything less than about 500 pg/L."


Snowmelt could be contaminated too. 

Johanna DeBiase

But Faust doesn't discount the new limits, pointing out that the EPA based them on current toxicology and health research. 

"Since the US EPA advisory level is lower than most analytical detection limits, it follows that practically any detections of PFAS will exceed advisory level," said Stu Khan from the University of New South Wales in Australia.

So the uneasy situation that the new research from Cousins and colleagues seeks to outline is this: Our world appears to be filled with a substance, largely produced during previous generations, that sticks around for a very long time. It would be helpful if there was more research on the potential health impacts of this stuff, but it's safe to assume we'd really be better off if it wasn't around at all, at least in our drinking water, that is. 

PFAS testing and filtration

This reality also further muddies the issue of whether I should be drinking the precious rain that falls on my desert home.

After all, Faust pointed out to me, "a 2021 study by a team of researchers from Johns Hopkins found PFOA concentrations in bottled water ranged from 170 pg/L to 2,000 pg/L."

So if bottled water has up to 500 times the EPA's advisable limit for PFAS, can my at-home rainwater-based Sodastream refreshments actually be much worse?

"If the remote area you currently live in is not vulnerable to long-range atmospheric transport of air-borne PFAS, you should be fine," Kurwadkar told me.

Of course, I have no idea how vulnerable I am to forever chemicals hitching a ride across the world high in the sky before dropping on my house inside a million tiny rain drops -- I didn't sign up for whatever premium subscription might tell me that.

There are ways to find out, though. Multiple companies offer home test kits to check for PFAS in your drinking water. A number of labs will analyze water samples for you for about $200 to $300, but I've ordered a kit from Cyclopure, which offers an $80 mail-in test. 

It will take a few weeks to get results for my own water, but I'll be sure to write an update when they come in. 

Meanwhile, Faust reminds me that there are options to ease postindustrial apocalyptic anxieties other than panicking over the toxic sky falling.

"I don't have a clear answer for you on whether switching water sources will lower your PFAS intake, but if you are very concerned, you could look into filtration systems with granular activated carbon for PFAS removal."

Adding a GAC filter to a home plumbing system is a relatively simple task, but it's still a plumbing job, which are rarely actually simple compared with most other tasks in life. Another option is a reverse osmosis filtration system, and there are countertop options available to filter drinking water that don't require any plumbing work. 

Sometimes when technology turns out to be toxic, our only choice is to turn to even more tech for salvation. So for now, I'm sticking with drinking from the sky while I wait for my results to come in and start comparing filtration options just in case.