The dangers of exploring storm drains

The 7 Deadly Dangers Of Exploring Storm Drains

Last Updated on September 7, 2019 by Urbex Underground

If you ever thought about exploring a storm drain, you may have asked yourself “are storm drains dangerous?”

The short answer is yes, exploring storm drains can be very dangerous. If you’re thinking about exploring storm drains there are some risks associated with drains that you’ll need to account for before exploring.

Last Updated on September 7, 2019 by Urbex Underground

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1. Deadly Gas

No, I’m not talking about a million farts trapped in a tube underground, but a combination of very deadly and sometimes odorless gasses that can cause you to lose consciousness or even stop breathing.

A common factor explorers don’t take into consideration is a danger they can’t see.

Sewer gas.

Sewer gas is a collection of gases from waste such as rotting organic matter, human waste, industrial chemicals, and whatever else anyone pours down the drain.

These gasses may include hydrogen sulfide, ammonia, methane, esters, carbon monoxide, sulfur dioxide and nitrogen oxides. Hydrogen sulfide has a rotten egg smell. If you encounter this smell and begin to show symptoms of coughing, watery or irritated eyes, trouble breathing, or a sore throat turn around immediately.

Prolonged exposure to this mixture of gasses can cause fatigue, pneumonia, dizziness and loss of appetite. If you continue to ignore these warning signs the gas will eventually become undetectable to your senses at 150 parts per million, and prove fatal at 300 parts per million.

These gases, along with a lack of natural flowing oxygenated air can be a deadly combination no matter how seasoned an explorer you are.

You can mitigate these risks following the steps above, or carry a H2S meter to alert you of dangerous air quality.

Don’t ignore the warning signs and never explore alone.

2. Sudden Flooding

You wouldn’t want to be down there right now.

Drains carry water.

Huge surprise.

But what most people don’t fully understand is just how incredibly fast drains can become filled, and how fast water can start moving.

Chances are if you are walking into a storm drain it is a CSO drain. A Combined Sewage Overflow system is where run off water from the street, gutters, and rain water flow out to the lake or ocean where they are diluted. This tunnel does not process human waste unless they is a rapid rise in water levels.

These massive drains are connected by dozens if not hundreds of smaller pipes and waterways that eventually dump out into a reservoir of some type. If there is a sudden storm, flood, or hydrant flush that occurs that single drain can become filled with an extremely aggressive current in a matter of minutes.

In some countries like Australia and Japan drains are built to redirect major flooding caused by monsoons and are as large as 30 feet in diameter.

Even a small ankle deep current is enough to sweep someone off their feet and literally down the drain. Their flashlight falls, they hit their head, they panic and start to get swept away in the darkness.

Not good.

The ultimate rule to take away from this: If it might rain, don’t go in a drain.

Always check the weather before going in, even if it looks clear out. If you begin to notice an increase in water, increase of current, or begin to hear rushing water in the distance leave immediately.

3. Getting Crushed

Don’t be like this guy. (He was fine by the way)

Manhole covers can weigh anywhere from 250-400 lbs.

That’s 180kg for the rest of the world.

Lifting manhole covers from below is extremely dangerous and really should never be done. Although the covers are built to stop them from falling inside the sewer, it doesn’t mean a car can’t run you over, or you slip and it hits you on the head.

If you absolutely need to open a manhole cover from below in case of an emergency Try to follow these steps.

Listen for traffic. It can be hard but if there’s any indication traffic is above, don’t open it. Find another way out.

Get a sturdy balance on a ladder or other surface and begin to push directly up with both hands. As soon as the cover begins to lift start pushing it toward one side of the hole. Do not attempt to push one side of the lid up and over.

4. Exploding

Only exit the hole when you’re sure the lid is completely off the hole, and the site is clear of traffic. Make sure to recover the hole when you’re out.

Drain explosion in NYC.

Are storm drains dangerous?

*Proceeds to explode*

One of the most prominent gases in sewer tunnels is methane. Methane is a byproduct of waste, and is flammable in the right conditions. One of the reasons manhole covers are so heavy and always have holes in them, is to vent that gas and prevent an explosion from sending the lid into the sky.

While exploring drains it’s best not to start fires, smoke, or do anything that would cause combustion. Explosions underground are rare, however if you’re exploring in a large city, like New York or Chicago the sheer amount of waste underground significantly increases your risk of methane buildup and risk of explosion.

5. Getting Lost

A complex inner city drainage system.

Getting lost in a storm drain is definitely a fear that most explorers have, myself included. Being underground with no clue where you are or how you can get out if definitely a danger, but can easily be mitigated with the right planning and gear.

While sewer systems and storm drains can definitely be complex, most run in straight lines parallel with the streets above them, branching out down side streets and funneling into one large cistern that moves the ground water to an outlet.

You may find that the further back you go, the smaller the tunnels get. You may have entered into a drain that is 20tf in diameter and find yourself in a drain that has now shrunken to 5ft.

Your chances of wandering down a maze of twists and turns and into a labyrinth of tubes is unlikely but not impossible. Drainage systems were built not to be complex, but effectively remove excess water in an efficient manner.

That doesn’t mean all drains are the same, especially in other countries. The ancient drains underneath Paris will drastically differ in architecture and layout than the more modern systems under the streets of New York City

Follow these few tips to avoid getting lost in dangerous storm drains.

Never go alone

This is a cardinal rule of exploring in general and you’ll probably hear it a million times. When you’re with someone else your chances of finding your way out when lost increase significantly.

Backup Light Sources

Bring two to three extra light sources and have them stored on you in separate compartments. This helps reduce the risk of all of your flashlights getting lost or destroyed by one single accident. I personally carry two spare flashlights in separate sealed compartments of my bag, as well as one that is attached to my belt loop, and another larger lantern source I might use for light painting, or just general exploration.

Mark Your Route

If a route starts to branch off and become complex, have something with you that will effectively mark your route. Duct tape can work great, however in underground humid environments you might find it difficult to get anything to stick to the side of the walls. Even so, it’s great to carry a roll with you anyway.

Spray Paint is a way better option in my opinion. It’s highly visible and unlike tying off a string or anchor point, it wont get tangled or disconnected. The only downside to this is if you’re caught police may think this is for vandalism. To me, this is a risk worth taking when venturing underground, as your chances of running into anyone is very low. You can always ditch the can if needed.

6. Electrocution

Trunks of cracked and semi exposed wiring in a drain system.

In some cases you may come across electrical wiring while underground. Your chances of coming across electrical wiring in drains is rare unless you’re in a large metropolitan area. Cities like New York sometimes run insulated electrical lines through the sewer systems to route power to certain areas.

These lines are supposed to be inspected for cracks and damage however I would never assume that these wires are safe. If you’re standing in water and accidentally grab on to one of these lines, you’re going to have a bad time.

Damaged electrical lines in storm drains is also one of the leading causes of manhole explosions. As the stagnant humid air begins to fill with methane gas the exposed wires create a spark and then…


If you see what looks like wires, or maybe a bundle of wires that run along the side or ceiling of the tunnel, stay clear and do not touch them.

7. Disease And Illness

Storm drains are dangerous and sometimes nasty.

Who knew?

Really though, there can be a significant risk to your health while in a storm drain. Like I said earlier, some drainage systems are combined sewage overflow, meaning that at some point in time raw sewage waste could be traveling through where you’re crawling around right now. Storm drains are untreated water, so there is a real risk of what you might encounter down there.

Exposing your skin and clothes to drains can put you at risk to picking up nasty bugs such as e coli bacteria, swimmers itch, fungal infections and a plethora of other rashes, ailments, and overall unpleasant experiences.

How do you avoid this?

Keep your body covered. Don’t expose your skin to bare surfaces, or walk around without any shoes on. Don’t lick anything while you’re down there either.

Also, wear a mask.

A particulate, or dust  mask won’t save you from poor air quality conditions, low oxygen levels, or methane gas, but it will help keep larger debris like mold spores and other poo particles out of your mouth and lungs.

When professionals who do maintenance in drains they usually send down robots that look like the mars rover’s little cousin.

If a human has to go down, they are equipped with an all in one helmet that provides outside oxygen and communications from above. They wear a full dry-suit as well as another protective puncture resistance covering.

I’m just going to assume you’re not willing to go to those lengths.

Have a separate set of clothes and boots to explore in. When after you’re out of the drain consider getting changed right away. Put your clothes and boots in a garbage bag, go take a shower, then dump your clothes into the wash. This might sound a bit extreme but there are some really strange and gross things you can find in storm drains.

Take all of this into consideration before exploring storm drains. So are storm drains dangerous? You bet.

Stay safe, and good luck.

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