Our Philosophy on Safety
A rebreather is a life-support system. It keeps you alive in an environment where you cannot breathe on your own. That’s not said to frighten you — it’s the starting point for everything we do on this site.
We built rebreathology.com because we believe that understanding how your equipment works — really understanding it, not just trusting a label — is the single most important thing you can do for your own safety underwater. An informed diver is a safer diver. That’s true whether you’re building from scratch, modifying an existing unit, or just trying to be smarter about the gear you already own.
But we also believe in honesty. And the honest truth is that no rebreather — commercial or home-built, cheap or expensive — is perfectly safe. Rebreather diving carries inherent risks that clever engineering can reduce but never eliminate. The hardware is only half the equation. The other half is you: your training, your discipline, your willingness to check, test, maintain, and never take shortcuts.
The Risks Are Real — For Everyone
Rebreather diving carries inherent risks that no amount of clever engineering can eliminate entirely. Hypoxia, hyperoxia, hypercapnia, caustic cocktail, flooding, and mechanical failure are all real possibilities — and they apply equally whether you’re diving a £15,000 commercial unit or something you’ve built in your workshop.
Commercial rebreathers have been involved in fatal incidents. So have home-built ones. The common factor in almost every case isn’t the hardware — it’s human error. Skipping pre-dive checks, diving beyond training limits, ignoring warning signs, or failing to properly maintain equipment. The machine is only as safe as the person operating it.
Building a rebreather is not, in itself, particularly dangerous. It’s mostly plumbing, some basic engineering, and a fair bit of careful thinking. The danger comes later — when you strap it on your back, put it in your mouth, and descend into water. That’s the moment when everything you’ve built, tested, and learned either works or it doesn’t.
What This Site Does — and Doesn’t — Provide
What we provide
Rebreathology.com is an educational resource. We provide information, explanations, design principles, engineering data, calculators, and build guidance — all shared freely under an open-source licence. Our goal is to help you understand how rebreathers work at a fundamental level, so that you can make informed decisions about design, construction, and operation.
What we don’t provide
This site is not a substitute for formal rebreather diving training. Reading every page on this site does not qualify you to dive a rebreather. No website can. Rebreather diving requires hands-on training with a qualified instructor, including emergency drills, bailout procedures, and supervised open-water experience.
We do not certify, test, inspect, or approve any equipment — including anything built using information from this site. We do not guarantee that the information here is complete, error-free, or suitable for any specific application. Engineering data, calculations, and performance figures are provided in good faith based on published sources, but they are for reference and educational purposes only.
Your Safety Is Your Responsibility
We live in an age where it’s tempting to assume that someone else has made things safe for you — that there’s a regulator, a standard, or a manufacturer standing between you and harm. And for many products in everyday life, that’s broadly true. But rebreather diving, especially with equipment you’ve designed or built yourself, sits firmly at the other end of that spectrum.
When you build your own rebreather, you are the designer, the manufacturer, the quality inspector, and the end user. There is no CE mark. There is no warranty. There is no customer support line to call if something doesn’t feel right at 40 metres. Every decision you make — from the size of your scrubber to the torque on a hose clamp — is yours, and so is every consequence.
That’s not a reason not to do it. It’s a reason to do it properly.
Rebreather diving can result in serious injury or death. This is true for all rebreathers — commercial, modified, or home-built. If you are not willing to take personal responsibility for your equipment, your training, and your decisions underwater, rebreather diving is not for you.
Before You Build, Before You Dive
If you’re planning to build and dive your own rebreather, here are the things we strongly encourage:
Get trained first
Complete a recognised rebreather diving course with a qualified instructor — ideally on a commercial unit — before attempting to dive anything you’ve built yourself. You need to understand rebreather failure modes, bailout procedures, and gas management from hands-on experience, not just theory.
Test rigorously
Every component and every assembly should be tested before it goes in the water. Leak tests, pressure tests, breathing resistance checks, scrubber duration validation — if you can test it, test it. Then test it again. Our guides include testing procedures for a reason.
Never dive alone
This should go without saying, but it bears repeating: never dive a rebreather — any rebreather — without a buddy who is capable of rescuing you. Rebreather failures can be sudden and incapacitating. A buddy isn’t optional; they’re your last line of defence.
Know your limits
Build experience gradually. Don’t take a freshly built unit to 50 metres on its first outing. Start shallow, start simple, and work up. There is no prize for going deep and no shame in turning a dive.
Maintain relentlessly
A rebreather that was safe last month might not be safe today. O-rings degrade, absorbent expires, sensors drift, and hoses perish. Treat maintenance as a non-negotiable part of ownership, not a chore you’ll get around to.
The safest rebreather in the world is the one attached to a diver who understands it completely, tests it obsessively, and never assumes it’s working — they check.
Nature of this site. Rebreathology.com is an educational resource. It provides information, explanations, design principles, engineering data, calculators, and build guidance for reference and educational purposes only. The content is shared freely under an open-source licence (CC BY-NC-SA 4.0 for content, GPLv3 for code).
Not a substitute for training. Nothing on this site constitutes formal rebreather diving training or certification. Reading this site does not qualify you to dive a rebreather. Rebreather diving requires hands-on instruction from a qualified instructor, including emergency drills, bailout procedures, and supervised open-water experience.
No certification or approval. Rebreathology.com does not certify, test, inspect, or approve any equipment — including anything designed or built using information from this site. No representation is made that any design, component, or procedure described here is fit for any particular purpose.
Accuracy and completeness. Whilst every reasonable effort has been made to ensure the accuracy of information presented, we do not guarantee that the content is complete, current, or free from error. Engineering data, calculations, and performance figures are provided in good faith based on published sources and should be independently verified before use.
Assumption of risk. Rebreather diving carries inherent risks including serious injury or death. By using this site, you acknowledge that you understand these risks and accept full personal responsibility for any decisions you make, equipment you build, and dives you undertake based on information provided here.
Limitation of liability. To the fullest extent permitted by law, the creators and contributors of rebreathology.com accept no liability for any loss, damage, injury, or death arising from the use or misuse of information provided on this site, whether in contract, tort (including negligence), or otherwise.
Component selection. When selecting components for any rebreather system, the complete system design must be considered to ensure safe, reliable performance. Function, material compatibility, adequate pressure ratings, proper installation, operation, and maintenance are entirely the responsibility of the system designer and user. Do not mix or interchange critical components between different designs or manufacturers without thorough engineering analysis.
Regulations and standards. The European standard EN 14143 covers rebreather design for commercial manufacture and provides useful engineering benchmarks, but it is a product certification standard that applies to manufacturers placing products on the market — not to individuals building for personal use. It is your responsibility to understand and comply with all laws and regulations applicable in your jurisdiction, including those governing compressed gas cylinders, filling, transport, and use. This site does not provide legal advice.
In Summary
We built this site because we believe knowledge should be freely shared, and that an informed diver is a safer diver. But information alone doesn’t keep you alive — judgment does. Use what you learn here wisely. Get trained. Test everything. Dive conservatively. Look after your gear. And never, ever assume that because something worked last time, it’ll work this time.
By using this site, you acknowledge that you understand the risks involved in rebreather diving and rebreather construction, and that you accept full responsibility for any decisions you make based on the information provided here.
Take your time. Be thorough. Stay curious — and stay safe.