Now I have seen many people around the different survival communities that I am a part of saying how unreliable the SODIS method is. Simply put, they’re wrong!
I understand that having to wait 6 hours in a survival situation before you can drink the water is a bit hard to face, but I would rather leave bottles of water out in the sun “whilst” I go out in search of other sources. If I am unlucky finding any other water sources then I’ll be glad I started this method sooner rather than later.
If the SODIS method wasn’t such an effective way of creating drinking water, then why are the World Health Organisation (WHO), UNICEF, and the Red Cross all recommending the SODIS method in developing countries?
What is SODIS?
SODIS is short for “solar water disinfection” and basically uses the rays of the sun to treat water to make it safe to drink. This method is often taught in developing countries which offers a great solution to their number one killer, diarrhoea. The SODIS method helps to prevent it.
Other than water and sunlight all you are going to need is a clear PET bottle. The UV-A rays in sunlight kill germs such as viruses, bacteria and parasites which can all put is into a very dangerous situation. The method is very simple and its application is safe. It is particularly suitable for treating relatively small quantities of drinking water.
How it Works
This is a super simple process though I would always prefer other methods such as boiling or using a filter straw such as the Sawyer Mini. Here is the SODIS method in four easy steps:
- Get a clean and clear PET bottle (thoroughly clean with soap and water if you’re unsure)
- Fill your bottle with water and replace the lid
- Lay your bottles of water down and make sure that they receive at least six hours of sunlight
- Drink up!
SODIS: Getting it Right
There are a few things that you need to remember and keep in mind about the SODIS method will give you a better chance of success in the wild. You can check these out below:
- Your bottle – you can use PET bottles or glass bottles though PET bottles are much more lightweight and less likely to break. Whatever bottle you choose must be completely clear although the blue tinge found in many PET bottles is fine.
- Turbidity – if you have collected your water from a source in the wilderness then there is a good chance that it is quite turbid. The more turbid the water, the less effective the method thus, the cleaner the water the better.
- Cloudiness – cloudiness affects the strength of solar radiation and thus also the effectiveness of the method and will not work properly during long lengths of rain. The general rule is that if less than half the sky is clouded, it will take 6 hours. If more than half is clouded it must be placed in the sun for two consecutive days.