Have you ever wondered whether or not it’s safe to drink rain water? Can drinking rain make you sick? Do you need to treat rain water? The short answer is that it’s usually safe to drink rain water fresh from the sky without using any special treatment. Of course, there are exceptions and ways to make rain water safer to drink. Here’s a look at when it’s safe to drink rain, when it’s unsafe, and how to make rain safer for human consumption.
Key Takeaways: Can You Drink Rain?
- Most rain is perfectly safe to drink and may be even cleaner than the public water supply.
- Rain water is only as clean as its container. If you collect clean rain in a dirty container, you get dirty water.
- Only rain that has fallen directly from the sky should be collected for drinking. Don’t drink rain after it touches plants or buildings.
- Boiling and filtering rainwater makes it it even safer to drink. But, rain water won’t make you sick even if you don’t boil or filter it.
- All rain, everywhere on the planet, now contains unhealthy levels of PFAS (polyfluoroalkyl substances) and microplastics, but most tap water does, too.
When You Shouldn’t Drink Rain Water
Rain passes through the atmosphere before falling to the ground, so it picks up dust, pollen, and contaminants in air. Normally, this isn’t a big deal, since you breathe in these particles anyway. However, it’s unwise to drink rain near the plumes of paper mills, chemical plants, or power plants. Similarly, don’t want to drink rain around hot radioactive sites, like Chernobyl or Fukushima.
Don’t drink rain water that has run off of plants or buildings because you could pick up toxic chemicals and pathogens from these surfaces.1 Similarly, don’t collect rain water from puddles or into dirty containers.
Rain Water That Is Safe for Drinking
Most rain water is safe to drink.2 In fact, most the world’s population drinks rain. The levels of pollution, pollen, mold, and other contaminants are low — possibly lower than your public drinking water supply. The levels of bacteria, mold, fungi, and viruses, are usually too low to make you sick. Plus, it’s easy to filter out the dust, pollen, occasional insect body parts, and pathogens.
Making Rain Water Safer
Two key steps you can take to improve the quality of rainwater are to boil it and filter it.1 Boiling water kills most pathogens. Simple filtration through a coffee filter removes dust, pollen, and insect pieces. Filtration through a home water filtration pitcher removes chemicals, dust, pollen, mold, and other contaminants.
Adding chlorine bleach is another water treatment method. It isn’t necessary to disinfect rain water, but there’s no harm in adding a small amount. If you choose to add bleach, the Centers for Disease Control recommends using 8 drops of bleach per gallon of water. Over time, bleach breaks down into water and salt.
How to Collect Rain for Drinking Water
How you collect rain water is important. Collect rain directly from the sky into a clean bucket or bowl. Ideally, use a disinfected container or one that was run through a dishwasher. Let the rain water sit for at least an hour so heavy particulates can settle to the bottom or pass the water through a coffee filter to remove debris. Although it isn’t necessary, refrigerating rain water slows the growth of most microorganisms it could contain.
Can You Drink Acid Rain?
Most rainwater is acidic, with an average pH of around 5.0 to 5.5.3 The natural acidity arises from a reaction between water and carbon dioxide in the air, much like the carbonation of soda. The slightly low pH is not dangerous. In fact, drinking water rarely has a neutral pH because it contains dissolved minerals. Approved public water could be acidic, neutral, or basic, depending on the source of the water. To put the pH into perspective, coffee made with neutral water has a pH around 5.4 Orange juice has a pH closer to 4. The pH of lemon juice is around 2. Dangerously acidic rain can fall near the plume of an active volcano. Otherwise, acid rain isn’t a serious consideration.
Microplastics and PFAS in Rain Water
A 2021 article in Science4 details the threat from plastics in all parts of the environment, including rainwater. In 2022, Cousins et al. released a study5 indicating all rain water has per- and polyfluoroalkyl substance (PFAS) contamination. This includes rain from remote areas, like the Himalayas and Antarctica. So, all rain contains unhealthy, possibly even dangerous levels of microplastics and PFAS. However, so do most public water supplies. While distilled and reverse osmosis water are initially free of these chemicals, the water often picks them up from storage containers.
- Joan D. Willey; Bennett; Williams; Denne; Kornegay; Perlotto; Moore (January 1988). “Effect of storm type on rainwater composition in southeastern North Carolina”. Environmental Science & Technology. 22 (1): 41–46. doi:10.1021/es00166a003
- Joan D. Willey; Kieber; Avery (2006-08-19). “Changing Chemical Composition of Precipitation in Wilmington, North Carolina, U.S.A.: Implications for the Continental U.S.A”. Environmental Science & Technology. 40 (18): 5675–5680. doi:10.1021/es060638w
- S. I. Efe; F. E. Ogban; M. J. Horsfall; E. E. Akporhonor (2005). “Seasonal Variations of Physico-chemical Characteristics in Water Resources Quality in Western Niger Delta Region, Nigeria” . Journal of Applied Scientific Environmental Management. 9 (1): 191–195.
- MacLeod, M.; Arp, H. P. H.; Tekman, M. B.; Jahnke, A. (2021). “The Global Threat from Plastic Pollution.” Science. 373 (6550): 61– 65. doi:10.1126/science.abg5433
- Cousins, Ian T.; Johansson, Jana H.; Salter, Matthew E.; Sha, Bo; Scheringer, Martin (2022). “Outside the Safe Operating Space of a New Planetary Boundary for Per- and Polyfluoroalkyl Substance (PFAS).” Environ. Sci. Technol. 56 (16): 11171-11179. doi:10.1021/acs.est.2c02765