Hello David (Solvatten),

I have followed this discussion, and I find it quite interesting. In my opinion, I feel like this is more of an alternative energy solution than it is a WASH one. This innovation offers warm treated water.... which raises the question, Did your team do any research in relation to 'water-heating' options for rural households? what were the outcomes?

I feel the technology contributes to a reduction in tree cutting and charcoal production as an immediate impact. Has there been thought on this impact?

Regards,
Chaiwe

Hello Elizabeth,

Thank you for your questions!

With the combined solar safe water treatment technology and solar water heater, we can kill two birds with one rock so to speak. Without the water being treated first before use, (tests show that Solvatten meets the highest standard of WHO guidelines for safe drinking water) warm water, as you point out can be a real danger as bacteria grows well in temperatures around +40°. But in the right range, water temperature can make all the difference. In Solvatten a synergetic effect occurs when solar disinfection is combined with heat pasteurization. An indicator shows when the process is completed at 55°C. This happens when the natural UVA and UVB has penetrated the membranes of the cells (the heat makes it easier for UV to penetrate the cells' DNA). 

To have access to hygiene and safe, warm water at home is something that every home, especially households with children, aspires to have and will benefit from - even households in tropical regions of the world. I have also briefly read the scientific studies that the wiki refers to that show that using warm water has no effect on reducing the microbial load on hands. It may in theory be so however people, especially children, find it more comfortable to wash hands and have baths in warmer temperature water. If we can help to change the hygiene habits of people not only water-borne diseases can be reduced, but also soil transmittable diseases and the spread of viruses can be better controlled. Please come back if you have more questions! It is super helpful to us and our mission to give people access to safe and also hot water at home in an environmentally friendly way.

See Solvatten in action here:  



David Wadström
www.solvatten.org

Hi David,

Yesterday, while editing the Wikipedia article on handwashing, I came across a statement that seems to contradict your assertion that warm water is more effective in killing germs than cold water. Here is what I read (with references):

en.wikipedia.org/wiki/Hand_washing#Warm_water

Warm water
Hot  water  that is still comfortable for washing hands is not hot enough to kill bacteria. Bacteria grow much faster at body temperature (37 °C). WHO considers warm soapy water to be more effective than cold, soapy water at removing natural oils which hold soils and bacteria. ^[37]  But CDC mentions that warm water causes skin irritations more often and its ecological footprint is more significant. ^[38]  Water temperatures from 4 to 40 °C do not differ significantly regarding removal of microbes. The most important factor is proper scrubbing. ^[39]
Contrary to popular belief, scientific studies have shown that using warm water has no effect on reducing the microbial load on hands. ^{[40] [39]}

(to see the references, click on the Wikipedia link above)

The references that you had shown in your attachment mix up the issue of handwashing in general compared to handwashing with warm water in particular.

I can see two aspects why warm water may lead to better results:
- The users might enjoy the handwashing more (although is this really an issue in hot developing countries?)
- The warm water removes oil, grease and fat better which might be important after food preparation or washing up dishes

But I don't think the warm water per se would kill any pathogens. For that, it is simply not hot enough. Am I wrong? Happy to learn.

Regards,
Elisabeth

Hello Charlotte,

Thank you for response!

Would you have any research to back warm/hot water being more effective to control COVID-19 than cold water?
Please see attached pdf with references to why warm water matters so much for hygiene. 

What is your evidence that people use the device for longer periods, after the initial novelty has worn off?
A large number of studies and projects prove that Solvatten motivates people to improve living standards as it is a convenient, no cost solution for the user. Since its inception, we have distributed the solution to 45 projects that reach more than 370,000 people in more than 20 countries, East Africa.  Whats making people use it? Overall respons is that it saves money (up to 50%). See references here: solvatten.org/references/

- Can it be produced locally or only in Sweden?
No, not at current set up of 120.000 per year.  But in theory, yes. With the right facilities - that is possible.
-Can the technology be replicated in a container larger than 10 litres?
in theory, yes. But mobility is important when off grid. Sun energy in constant motion over the sky makes mobility a better solution. 
- Of the 8 countries tested, do we have any in Africa? This technology would really be helpful here.
Please see references for more information.

Happy to make an online presentation if any more questions?

Best regards
David

Dear David,
Thank you for your post. Feel free to share more posts that are as beneficial and aim to improve hygiene. This is quite critical especially during this time of COVID -19. A few questions for clarification:
-  Would you have any research to back warm/hot water being more effective to control COVID-19 than cold water?
-What is your evidence that people use the device for longer periods, after the initial novelty has worn off?
- Can it be produced locally or only in Sweden?
-Can the technology be replicated in a container larger than 10 litres?
- Of the 8 countries tested, do we have any in Africa? This technology would really be helpful here.

Looking forward to your response.
Regards
Charlotte 

Among the most important preventive strategies to control the transmission of the Covid19 pandemic is handwashing with warm water and soap, as it has shown to be very crucial. Better hand hygiene is the primary measure to combat the spread of infectious illness. It is also well established that hand washing with clean warm water and soap can greatly reduce the chances of spreading or getting germs when done correctly. The mechanical action of scrubbing loosens up the dirt and microbes on hands and the soap picks up and binds to the microbes so that the water can wash away.  Additional advantage of using clean warm water is that it is usually more comfortable to use than cold water and modern soaps are designed to be most effective in warm water. Availability of clean, warm water will bring convenience to the cleaning for children. Thus hand washing is the best way to prevent communicable disease. 

Training and Nudging Technology can partly solve the problem
Solvatten is a 10 liter jerrycan made in Sweden that heats and treats unsafe water using natural UV and sun heat.  With no chemicals or batteries, only a few hours of exposure to the sun's UV and heat will make the water safe to drink. Tests have shown that proper use of Solvatten will produce purified water, which meets the WHO guidelines for drinking water (< 1 Ecoli/100ml). Solvatten AB has carried out many field and laboratory tests to confirm this, in 8 countries in different climates and conditions (please request if you want more information).

Solvatten is uniquely positioned to also help nudge hygiene behaviour for hard to reach target groups as it provides households with clean hot water, (up to 75°C) which helps motivate  people to improve living standards in a convenient way. 



We work in partnership with governments, local organisations and corporations to provide Solvatten to millions of people living off-grid. We have since start 2007 initiated 45 projects reaching +300.000 people living in +20 countries where the need is great. Please contact us for more information. 



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