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You have here a wide range of different products, most of them being household water treatment (HHWT) solutions that could be used during emergency responses, when sources of potable water are not available; but one – from Water Makers – being a reverse osmosis desalinization system.

Then the choice depends on your objectives:

Why do you want to treat water? What are the available sources of drinking water? How many people are affected? After the emergency response – during which portable water treatment kits could be used, what longer term solution are you planning for drinking water? What is your budget available? And finally, which system/technology would be accepted by the users?

Firstly, before making any choice, keep in mind that the chlorine, when properly used and dosed, has, what we call a “persistent effect”: you always add a little bit more of chlorine than needed, to make sure that you have some free residual chlorine in your water.

During emergency response, when people might be exposed to diseases or outbreak and/or when hygienic practices of people are not healthy, the drinking water could be re-contaminated after treatment – i.e. through dirty hands or buckets. So, even if the water has been filtered using Waves for Water or Sawyer filters, it could be contaminated afterwards, through risky hygienic practices. Thus, purification tablets/chlorine tablets (supplied with the Dayone response water bag and by the internationally known Aquatabs offering a wide range of products) would properly treat your water and a remaining/extra quantity of chlorine present – called “residual chlorine” – in the treated water would prevent opportunistic re-contaminations.

Even if you’re working in an environment where the hygienic practices seem to be good, I would recommend the use of chlorine for the treatment of water, which could be combined to the filtration: first, filter the water (which will remove lots of contaminants and suspended matters) and then disinfect it (the filtration would reduce the quantity of chlorine required to treat the water) making sure that you’ll have “free residual chlorine” after treatment.

Of course, if you’re looking for a system that you may use during your treks in the pristine mountains, you can use the filter bags without chlorine to filter the water from the torrents!

Cost and time

Remember that if you plan to distribute massively HHWT technologies, you’ll need to properly train the users and monitor the use. Then, when you target a large number of affected population, it will be more expensive to organize a distribution of HHWT technologies than to protect and use a source of good quality water. But during an emergency response, it could be the only solution; which should be a temporary solution.

Chlorination at the points of use

Under extreme conditions, you may need to set up water treatment at the point of use. It’s quite common during cholera/Ebola outbreak. You’ll set up different chlorination points which consist of some trained technicians chlorinating the collected water directly into the buckets carried by the users. The chlorination points could be at the water source/water point or distributed strategically in several locations, visible by the users. This could be an efficient temporary solution, but time and money consuming.

Finally, have a look at your budget constraints and ordering/delivering procedures to select the most appropriate technology. I don’t know where you’re working and under which conditions, but importing these filter bags might take time and money; while chlorine may be more easily accessible locally or in the region. And there are DIY ways of filtering water.

Have a look to these Factsheets from WEDC, WHO and the International Federation of the Red Cross and Red Crescent on the HHWT techniques:

https://www.lboro.ac.uk/well/resources/technical-briefs/58-household-water-treatment-1.pdf

https://www.who.int/water_sanitation_health/emergencies/WHO_TN_05_Emergency_treatment_of_drinking_water_at_the_point_of_use.pdf?ua=1

https://www.ifrc.org/Global/Publications/disasters/142100-hwt-en.pdf

Desalinization of water Looking at the Water Makers technology, this is something completely different. This is a technology to desalinate the sea water. The reverse osmosis (RO) is quite efficient to treat the sea water and could be useful when fresh water is not available or contaminated. But the RO requires huge amount of energy and it could be more expense than protecting/rehabilitating/improving existing fresh water sources.

Again, I would then consider the different options available:

What are the existing sources of drinking water? Are the hygienic practices safe? Are there any risks of diseases outbreak? What are the local practices in terms of household water treatment? What are the locally available technologies/systems? What is acceptable by the users (the use of the system and the taste of water)? What is the budget available? What is my timeframe? …

I hope it was useful.