How Do People Get Oxygen And Drinking Water Inside A Submarine?

Table of Contents (click to expand)

Oxygen is supplied onboard a submarine through pressurized tanks or an oxygen generator, while drinking water is obtained by desalinating seawater.

A submarine is a special ship designed to operate independently underwater for days. The most notable thing about a submarine is that it stays underwater for days. This leads to a natural question – if a submarine is constantly surrounded by water, how does it have enough drinking water for its crew members?

Submarine against evening sky

Even more importantly, how do the crew members get breathable oxygen, the most crucial requirement for human life?

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Life Support Systems In Submarines

Due to their multifaceted usefulness, submarines have become essential to naval armies from various countries worldwide. One of the most common applications of submarines is to surveil and defend a country’s maritime borders. Human-crewed submarines are deployed underwater along a nation’s coastal borders to look for suspicious activities in the waters.

Interior of the tourist submarine Atlantis whilst submerged. (Image Credit: Leonard G. / Wikimedia Commons)

This necessitates deploying a considerable number of “manned” submarines underwater. A submarine can typically support around 50-100 passengers. Therefore, you need a system in your submarine that can take care of the water needs of all passengers, maintain comfortable temperatures onboard, and, most importantly, provide fresh, breathable air without interruption.

Also Read: What Makes A Submarine Implode?

How Does A Submarine Crew Get Drinkable Water Onboard?

Submarines are surrounded by water almost always, but that’s seawater, which is salty. As such, it cannot be directly used by the crew or even to maintain the engines and batteries of the submarines, which consume around 4000 gallons of water per week. (Source)

To get freshwater, submarines have a distillation apparatus that heats seawater to create water vapor, removing salt. The water vapor is then condensed to create freshwater that can be used for drinking, personal hygiene, and cooking.

Also Read: Why Do Submarines Have To Resurface At All? Can’t They Remain Submerged Indefinitely?

How Does The Crew Get Breathable Air Inside A Submarine?

There are different ways to release oxygen on a submarine, such as compressed tanks, an oxygen generator, or an oxygen canister that works through electrolysis. Oxygen is either released periodically throughout the day at specific intervals or when the automated system detects a drop in oxygen levels.

Removal Of Carbon Dioxide

Breathing is a two-way process – we inhale oxygen and exhale carbon dioxide. We don’t need to worry about the carbon dioxide we exhale in open spaces. Still, in a closed metal tube hundreds of feet beneath the water’s surface, it can become a serious threat to survival if not removed periodically. As a result, it’s just as important to eliminate the carbon dioxide that the crew members constantly release as it is to provide oxygen.

This is where scrubbers come in.

Submarine carbon dioxide scrubber
A basic representation of a scrubber’s components and mechanism

They use soda lime, a mixture of chemicals (sodium hydroxide and calcium hydroxide), to eliminate carbon dioxide from the atmosphere and prevent carbon dioxide poisoning. Soda lime is commonly used in closed-breathing environments, such as submarines, rebreathers, and recompression chambers. It captures the carbon dioxide produced by the crew members and removes it from the air using chemical reactions.

Removal Of Excess Humidity

Excess humidity can harm the inside of a submarine, as it can condense on the walls and equipment. To address this issue, submarines are equipped with ‘dehumidifiers’ that prevent moisture accumulation within the chamber due to breathing and perspiration.

Overall, the safety and comfort of the passengers aboard a submarine are ensured through sophisticated machinery onboard. However, being confined to a metal tube hundreds of feet underwater without sunshine and suffering from homesickness can be a lot less thrilling than it may seem.

Last Updated By: Ashish Tiwari

References (click to expand)
  1. GELLER, R. E. (1968, November). Oxygen safety - Submarine to aircraft. Journal of Aircraft. American Institute of Aeronautics and Astronautics (AIAA).
  2. The Machinery of Modern Submarines.
  3. Lee, D., Lee, J., & Lee, K. H. (2002). A Decision-Support System to Improve Damage Survivability of Submarine. Developments in Applied Artificial Intelligence. Springer Berlin Heidelberg.
  4. Loveman, G. A. M., & Edney, J. J. E. (2021, February 3). Predicting the effect of decompression sickness on survival following submarine tower escape. Journal of Defense Analytics and Logistics. Emerald.
  5. Shadle, T., & Daley, T. (1991, July 1). U.S. Navy Submarine Life Support Systems. SAE Technical Paper Series. SAE International.
About the Author

Ashish is a Science graduate (Bachelor of Science) from Punjabi University (India). He spearheads the content and editorial wing of ScienceABC and manages its official Youtube channel. He’s a Harry Potter fan and tries, in vain, to use spells and charms (Accio! [insert object name]) in real life to get things done. He totally gets why JRR Tolkien would create, from scratch, a language spoken by elves, and tries to bring the same passion in everything he does. A big admirer of Richard Feynman and Nikola Tesla, he obsesses over how thoroughly science dictates every aspect of life… in this universe, at least.

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