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As part of disaster preparedness, we need to think about our water needs. Most humans need water to survive. (Technically, all humans, but my sister would disagree with me and claim she can survive off Diet Dr. Pepper). During non-disaster times, we have access to water through our jurisdiction such as city water, a water well, or even through purchasing bottled water. Even if your area has additional options, disasters tend to contaminate water and/or cut off access to water sources. Identifying water purification versus water filtration needs in advance is a critical part of disaster and emergency preparedness.

This means we need to prepare for the potential of not having fresh water. On the Disaster Preparedness Checklist article, I mentioned that the Ready.gov guidance mentions bottled water in commercial bottles. I’m not a fan of this strategy and recommend storage in something sturdier. You can see some recommendations for long-term water storage here. Then, we need to explore water filtration and water purification for both short-term and long-term needs.

What About Water Storage?

Even though the disaster kit checklist recommends storing water for several days per person, there are challenges with this. In fact, the recommendation from Ready.gov is that we use commercial bottled water. I have 2 core issues with this suggestion.

First – I wonder if the author of that page drinks bottled water. It seems all water bottling companies have shifted their packaging (supposedly to reduce plastic usage) to flimsy junk that sometimes breaks just trying to open the bottle.

Second – there is continued discussion on the challenges of commercial PLASTIC bottles leaching chemicals into the water over time. While this is SLOWED by keeping the bottles in cool (but not too cold), dark places (as recommended by Ready.gov), it is not eliminated. This article from The Plastic Pollution Coalition discusses the dangers of drinking bottled water in general. Adding the challenges of storing plastic bottles during extreme temperatures makes plastic contamination a higher risk than normal. Explore various water storage options in this article.

Regardless of water storage, your supply could get contaminated (or you just want to filter out potential PFAS from your stored water). Another potential challenge is an extended period of water contamination. In Hurricane Helene, there were reports of some jurisdictions not having drinkable water for two months after the hurricane. While the general instruction is to boil water, this doesn’t meet everyone’s needs. Let’s explore the difference between water purification and water filtration for a disaster or community crisis.

What Is Water Filtration In Disasters?

Water filtration is the process of removing elements from water with the use of some sort of “filter”. A common filter is a charcoal filter. If you have a fish tank, you might have a charcoal filter for your fish tank (but don’t drink the fish water). Like filters in a fish tank, a filter takes out some things but not all things.

For water following a disaster, filtration can remove various elements, but not all of them. Since the process of filtration relies on a filter, only the items that are too big to pass through the filter are removed. Even then, if the filter is not clean enough, it can clog or damage the filter so even larger particles pass through. Consider that components like bacteria are very small and can make it through filters that are not made to stop bacteria. With contaminated water, some chemicals and toxins may be small enough to pass through a standard filter. Water purification can address some or all of these issues depending on the type of water purification.

What is Water Purification in Disasters?

This one is a bit trickier. Technically, “purification” should be better – but only if it’s done right. True purification would act as a filter (removing substances that don’t belong), kill any type of bacteria or other biological elements, and neutralize any other chemical or toxic substances. Unfortunately, most people think that purification tablets are enough to meet the “purification” standard. It makes sense considering the tablets say “purification” in the label.

Water purification tablets do help! The problem with purification tablets is that these do not address all the potential issues with contaminated water. Not all tablets are equal and most do not address heavy metals, many chemicals, pesticides, or other contaminants. It’s one thing to use the purification tablets when you’re out camping and using water from a river (and I still struggle with just purification tablets in that situation). Contaminated water following a disaster can have a wide range of unknown contaminants including chemicals from cars and buildings, pesticides or herbicides from farms (or just a neighbor farming), the meth lab (or fentanyl supply) that no one knew about, etc.

Reverse Osmosis – Beyond Water Purification Tablets

If we want to purify water, we need to do more than use purification tablets so we can remove substances, and neutralize those elements we don’t want in the water. Of course, we don’t want water that is removed of all beneficial elements like that in distilled water (more on that in this article). Our body still needs electrolytes and minerals to avoid other complications.

One of my favorite purification methods is reverse osmosis. Reverse osmosis still uses a filtering type process, but the filters are at a nanometer level (that’s small). There’s more scientific stuff to it, but the short version is that it’s a better purification process. Almost everything we can identify can be filtered out through reverse osmosis. The largest challenge with these types of systems is that larger elements can damage the reverse osmosis “filters”. When you’re filtering tap water (which is already treated and filtered), you don’t expect larger particulates. Using reverse osmosis on potentially contaminated water means we need to consider those issues we wouldn’t normally need to consider. More on that in a moment.

With recent studies revealing PFAS (perfluoroalkyl and poly-fluoroalkyl substances) or “forever chemicals” in natural water sources, reverse osmosis feels necessary for daily use. Of course, that’s a Kim bias…but also a recommendation. So far, studies show that reverse osmosis can remove the PFAS/forever chemicals. If it can take those out, it’s removing a lot of bad stuff! Reverse osmosis is a great option, though there are not a lot of options for systems that do not require electricity.

What About Bleach For Water Purification?

Bleach is similar to water purification tablets, though it tends to be much cheaper. The biggest challenge with bleach is that it is highly toxic if you do not have the right proportion. Additionally, bleach doesn’t remove everything. While bleach used to purify water is one method that CAN be used during an emergency, it’s not typically the first recommendation. This article from healthline.com discusses some of the potential side-effects of bleach.

Since I’ve known too many people who get sick from using the bleach method, I just don’t recommend it unless there are absolutely no other alternatives so I’m not going to share how to use bleach. I don’t even include it in my recommended steps simply because other methods can do the same job and not risk your life with the supposed-to-be “solution”.

How Do We Implement Water Purification and Water Filtration?

It seems like we would want purified water that includes the filtration elements of removal of components. So, how do we do that?

It is important to follow the instructions provided by your local government. Keep in mind that during a disaster officials may not know of additional contaminants specific to your area or your water supply until much later in the disaster response. Ultimately, you have the right to protect yourself and your family from potentially deadly water by implementing the best possible strategies.

It’s impossible to give a solution that fits all scenarios, but here is a series of steps that can help you minimize potential exposure to contaminants (and this is just a suggestion to help you prepare, so you need to adapt this based on your specific situation and local guidance following a disaster).

Example Water Filtration and Purification Strategy

1. Use a comprehensive water testing solution to identify potential contaminants (this still doesn’t test for every possible problem, so even if these return acceptable results, at least follow the local guidance for water – such as boiling if advised). See this article on water testing kits.
2. Filter water first through standard water filters – you’ll see I mention reverse osmosis in suggestion 4 which includes filtration. Since reverse osmosis uses much smaller (nanometer) filtering, you don’t want to risk damaging your reverse osmosis system with larger particles. Use a regular water filter first to help remove foreign substances that are larger. Different water filters have different sizes, so it’s best to use a water filter specifically for removing substances. See this article on the best portable water filtration systems for your disaster preparedness kit.
3. Boiling water – this process is sometimes frustrating if your water supply is limited. Yet, boiling water kills germs that are hardy and can even sneak through filtration. Just keep in mind that gas and electricity may not be available following a disaster, so you need an option for how to heat the water to boiling.
4. Use a reverse osmosis system to help remove any remaining contaminants. We’ve used a standard filter first and now we’re going to get out everything else we can.
5. Test Again. If the original testing showed contaminants, test again to verify those contaminants are removed. If the first test didn’t show contaminants, you can still test again for peace of mind or just to double-check.

Final Thoughts on Water Filtration and Purification

While I don’t include water purification tablets in these steps (you could add it before the boiling water), it’s a good idea to have some on hand anyway. Additionally, reverse osmosis is not a simple process (but there are machines that do it all). There have been advancements to make reverse osmosis systems small enough to fit on your kitchen countertop, and some claim to be portable. Unfortunately, most of these systems require electricity. That means you’ll need backup power for disasters that knock out power and contaminate water. I discuss battery backups in this article.