Is Stagnant Water Safe To Drink?

Stagnant water is ugly and annoying, but is it actually dangerous to your health? Are you asking for trouble by drinking stagnant water or should you search for a flowing water source? Is stagnant water safe to drink?

Stagnant water is a breeding ground for bacteria, viruses, mold, insects, and vermin and it can be extremely dangerous to drink. Most of the dangers of stagnant water will be eliminated with a water filter or purifier, but it’s always better to search for flowing water. Flowing water has many of the same issues so it still needs to be filtered/purified, but you’re less likely to run into dangerous pollutants.

It’s never a good idea to drink out of standing water. Not only are they unpleasant to look at, but it can pose serious health problems. In the rest of this post I’ll explain why stagnant water is dangerous and explain how to purify/filter it a backcountry situation.

What Is Stagnant Water?

Water stagnation occurs when water stops flowing. It’s a major environmental hazard and can lead to dangerous consequences if you drink it. Stagnant water is filled with bacteria, mold, viruses, insects, and vermin waste/disease.

There are a lot of different sources of standing water. You can have water body stagnation in swamps, lakes, ponds, lagoons rivers, etc., pooling surface and ground water stagnation from recent flooding, and trapped water stagnation where water s trapped in human artifacts (buckets, cans, planters) and natural containers (hollow tree trunks, leaf sheaths, rocky surfaces).

All of these sources are the perfect breeding ground for dangerous pollutants. Generally speaking, the longer water sits the more dangerous it will be. A cup of water left out on a table can be safe to drink for days, but you wouldn’t want to drink it after a month.

Flowing water is safer than standing water, but understand that every backcountry water source needs to be filtered/purified before it’s consumed. A flowing stream or river won’t contain as much pollutants, but you can still get sick from drinking it. You should always use a water filter or purifier when drinking water in remote wilderness situations.

Backpacking water filters like the Sawyer Mini or Sawyer Squeeze are cheap and filter out 99.99% of harmful bacteria, protozoa, sediment, cysts, and microplastics. Flowing water may be safer to drink than standing water, but it’s always better to err on the safe side when camping in remote areas.

Can You Get Sick From Stagnant Water?

Stagnant water is ugly and annoying, but can you actually get sick from it? The answer is an emphatic “YES”! Let’s look at some of the reasons why drinking stagnant can be dangerous to your health.

Drinking stagnant water is dangerous to your health for five main reasons: bacteria, viruses, mold, insects, and vermin. It’s not just dangerous to a humans health, it can also be dangerous for your pets. If you have standing water around your property you should always try to eliminate the source.

1. Bacteria: Stagnant water provides the perfect breeding ground for bacteria. Some types of bacteria are relatively safe, but other varieties can be extremely dangerous. Drinking stagnant water can make you very sick. It will cause a bacterial flu giving you diarrhea, nausea, fever, vomiting and can lead to extreme dehydration. That can be a serious issue in a backcountry survival situation.
2. Viruses: Viruses aren’t a problem throughout most of the United States and Canada, but standing water is a breeding ground for viruses in underdeveloped countries and anywhere without proper waste disposal methods (popular campgrounds). Viruses are microscopic and smaller than bacteria so water filters can’t get rid of viruses. You need to use an alternative purification method like boiling water, chemical solutions (aquatabs), or UV Purifiers (Steripen) to kill viruses.
3. Mold: Mold is just like bacteria! It loves a moist environment and thrives in standing water. Some molds are safe, but others are very dangerous to your health. It’s best to avoid any water source that has obvious signs of mold.
4. Insects: Insects like mosquitos are attracted to standing water. They can’t lay their eggs in flowing water so they look for standing water to make nests. Mosquitos carry a wide range of viruses including west nile, zika, and malaria. This isn’t a huge issue with drinking the water, but it can cause other health issues if you get bit by them.
5. Vermin: Vermin like mice, rats, possums, skunks, etc. will be attracted to standing water. They have strong immune systems and are always looking for water sources. If there’s standing water there’s a good chance it’s been visited by local wildlife. Vermin aren’t just irritating, they also spread waste and carry diseases that could put your health at risk.

It’s always safer to use flowing water as a water source, but that doesn’t mean you should completely avoid stagnant water. There are ways to filter and purify stagnant water if it’s the only available water source in remote camping areas. Let’s explain how to filter and purify standing water so it’s safe to drink.

What Happens If I Drink Dirty Water?

If drinking water contains unsafe levels of contaminants it can cause serious health effects. Contaminated water can cause diarrhea, vomiting, cholera, dysentery, typhoid, and even polio. Drinking contaminated water is estimated to cause 485,000 diarrheal deaths each year.

The main issue in a camping/backpacking setting is diarrhea and vomiting from contaminated water sources. You’re body expels more water than it can absorb which leads to extreme hydration. Drinking contaminated water in a backcountry setting can be extremely dangerous.

You Can Filter Or Purify Standing Water

I don’t recommend seeking out stagnant water sources, but there are times when that’s all you can find in remote backcountry settings. Go with a flowing water source if possible, but you drink out of standing water if that’s all you can find. Just make sure you use a water filter or some other kind of water purification method. Here are a few of your options for water filtration/purification starting with the most popular.

• Water Filters: Water filters are the primary means of water purification for backpackers and campers. Backpacking water filters remove 99.999% of bacteria (salmonella, cholera, E Coli, etc., protozoa (giardia, cryptosporidium), and microplastics. They also get rid of sediment and algae making the water taste better. The only downside to water filters is they can’t remove viruses since they’re smaller than most filter elements. There are water filters that can handle viruses, but they clog easily giving you a limited lifespan.
• UV Purifiers: UV purifiers use a UV light to kill everything that’s in the water including viruses. You only have to worry about viruses in underdeveloped countries with pour waste disposal methods, around farms, and near popular campgrounds. The Steripen is the only UV Purifier that’s currently on the market. Just dip it into the water, turn it on, and your waters safe to drink in seconds. You may still want to use the filter to make your water taste better by removing sediment/algae.
• Chemical Treatment: Chemical treatment methods will also handle viruses, bacteria, and protozoa. Chemical treatments like Aquatabs use chlorine to kill everything in the water and are highly effective, but they take a while to use. Just drop the tablet in your water supply and wait at least 30 minutes for it to purify your water. It is a bit of a guessing game, because it can take longer to work depending on the temperature.
• Boiling Water: Boiling water over a stove is another way to purify your water, but this method is a pain in backcountry situations. You have to carry in a lot of fuel, wait for the water to boil for 1 minute, and then let it cool down to a safe drinking temperature. Boiled water can taste flat so try to aerate the water before drinking it.

Filtering Standing Water

Water filters are by far the most popular water sanitation method in the United States, Canada, and remote wilderness where you don’t have to worry about viruses. They remove 99.999% of bacteria, protozoa, organic compounds, mold, sediment, and microplastics from backcountry water sources. Backpacking water filters are affordable and you can clean out a large amount of water fast.

There are lots of different water filters available, but I prefer the Sawyer Mini Water Filter. It’s cheap and can be used in a wide variety of applications. Screw it onto your water bottle, use it as an inline filter with a hydration pack, or set up a gravity filter for large groups. It can filter up to 100,000 gallons of water so it’s durable enough to last a long time in the wilderness. Just make sure you regularly clean and backflush the filter to prevent clogs from sediment and mold.

There are also pump style water filters like the MSR Minoworks and Katadyn Hiker Pro. Pump style filters are great for filtering a large amount of water fast, but they’re expensive. They make collecting water easier in shallow water beds, but they’re bulky and more likely to break.

The only downside to water filters is they can’t kill viruses. Viruses are only found in developing countries without strict waste disposal methods. Sewage seeps into the local water supply polluting the surrounding areas.

Purifying Viruses In Underdeveloped Countries

There are a few options to deal with viruses in your water supply. You can boil water, use chemical treatments (aquatabs), and use UV Purifiers (Steripen). Boiling water requires a lot of fuel and chemical treatments take a long time to work so a UV purifier is the best bet.

The Steripen is the only UV purifier I’ve hear of and by far the most popular way to kill viruses. They use a UV light to kill everything that’s in the water including viruses, bacteria, protozoa, and any other germs that could make you sick. You still want to use a water filter to remove dirt, sediment, and algae, but the water would be safe to drink without a filter.

Flowing Water Still Needs To Be Purified

Flowing water is less likely to contain dangerous bacteria, protozoa, and other things that make you sick, but it still needs to be filtered or purified. You don’t want to be in a remote camping area and accidentally catch something. That can be deadly since it can lead to dehydration from fever, diarrhea, and vomiting. All backcountry water sources need to be filtered or purified using one of the above water purification methods.

Water Sources To Avoid

Here are some general rules that I use when searching for remote water sources. The goal is finding the best available water source. That’s usually a running river or creek, but sometimes you’ll need to use what’s available. A high quality water filter and purifier will make even the dirtiest water sources safe to drink.

1. Puddles and Standing Water: Don’t drink from puddles and other standing water sources where there’s no inflow and outflow of water. I’ve already went over this in detail above so I won’t bore you, but standing water is a breeding ground for dangerous pollutants.
2. Water Near Towns/Cities: Avoid taking water from any source that’s downstream from towns, cities, and industrial manufacturing areas. These sources are more likely to contain viruses and chemical pollutants from dangerous runoff. The Cuyahoga River (outside Cleveland) catching on fire should give you a good enough reason to avoid city runoff.
3. Farm Water Runoff: This is especially important near cattle, pig, and horse farms. Domesticated animals release dangerous bacteria and disease in their feces. Rain washes it into the surrounding areas infecting the local waterways with disease.
4. Tannic Water: Red and orange colored tannic water is filled with tannins. This is usually found in heavily forested areas when leaves start to drop in the fall. Tannins don’t prevent a health hazard, but it will quickly clog up your water filter.
5. Water Falls and Cascading Rapids: This water isn’t particularly dangerous to drink, but there will be a lot of sediment in the water. You can filter out sediment using a backpacking water filter, but it will clog up the filter. Drinking from sediment filled water will require lots of backflushing to clear filter clogs.
6. Murky Sediment Filled Water: Once again this is a sediment issue and not particularly dangerous to your health. Sediment filled water will quickly clog up your water filter.

How Long Is Stagnant Water Good For?

You can’t just purify/filter your water and let it sit there. It will slowly start to grow bacteria, mold, algae, and everything else that caused safety issues in the first place. Try to drink the water within a couple days so there’s not enough time for dangerous pollutants to grow.

So how long is stagnant water good for? That really depends on how the waters being stored and a host of other external factors. An open cup of water will be safe to drink for up to 3 days while a sealed barrel/jug of clean tap water can last 6-12 months. Purified water sealed in a food grade container like you buy at a grocery store can last for well over 2 years. It all depends on how the waters stored and whether or not bacteria was introduced during fillup.

You can always extend the life of stored water by purifying it with a bottle of bleach. All you need is a 1/4 teaspoon of bleach per gallon of water. It’s always safer to add a little bit more bleach than necessary for long term storage so a 5 gallon water bottle would need 2 teaspoons of bleach and a 55 gallon drum would need a 1/3 cup of bleach to purify it. That will restart the clock killing everything inside and give you six more months of pure water.