Compiled by:
Gabrial Erismann (Antenna Foundation), Raphael Graser (Antenna Foundation)

Executive Summary

Chlorination, which means adding active chlorine (sodium hypochlorite) to water, is the most common method used for disinfecting of drinking water. Active chlorine destroys or inactivates most pathogenic microorganisms, including parasites, bacteria and viruses with a very high reliability. The WHO estimates that chlorination is the most secure, effective and economic option. Yet, generally speaking, chlorine is not produced in low-income countries, but imported in the form of tablets or bleach, at relatively high cost. WATA® is technology and approach developed by Antenna Foundation which integrates health education with the local production of chlorine by electrolysis (through the WATA® device) in a sustainable supply chain, making safe water treatment a profitable activity.

In Out


Drinking Water

To prevent waterborne diseases it is fundamental to deliver safe water at the point of use. The 2017 published Joint Monitoring Programme (JMP) report from WHO and UNICEF shows that recontamination occurs very often between the point of collection and the point of use and thus leads to an increase in waterborne diseases. It is thus fundamental to find a solution to enable populations to address their drinking water problem in a self-sufficient and perennial way. To respond to the need of BoP communities to have access to simple and affordable water treatment methods at the household level, Antenna Foundation has developed a range of WATA devices (Mini-WATA®, WATA-Standard®, WATA-Plus®, Midi-WATA® and Maxi-WATA®), and control reagents (the WataBlue® & WataTest®). Until today WATA® kits have been used in over 100 countries.

WATA® Device

The Range of WATA® Devices

The Range of WATA® Devices

The WATA® is a handy, robust device designed specifically for the production of active chlorine through the electrolysis of salted water under conditions in developing countries. The resulting solution can be used for drinking water disinfection (1 Liter of chlorine per 4.000 Liters of contaminated water) since the strong oxidising power of the chlorine will destroy most of the pathogenic germs and the water will be drinkable after 30 minutes.

 Dosage for Chlorinating Drinking Water

Dosage for Chlorinating Drinking Water 

This sodium hypochlorite solution can also be used as a disinfectant for home use. The WATA® system is extremely adaptable to meeting the disinfectant needs of larger institutions such as health facilities also. Additionally, the sodium hypochlorite solution is similar to Dakin’s solution, a neutral disinfectant, and can be used directly for cleaning wounds.

Use fo WATA®

Preparation of Disinfectant Solution

Preparation of Disinfectant Solution

Preparation of Disinfectant Solution

The device requires only water, salt and electricity to function. It is important to note that clear water is a requirement for both the production process and as an input for the disinfection process. For the production process, highly turbid water will interfere with the electrolysis process and the resulting solution may not be at 6g of active chlorine per liter. If the turbidity (a measure of the suspended solids in the water) of the water to be disinfected exceeds 5 units of turbidity (NTU), it could diminish the treatment’s efficiency and not guarantee adequate inactivation of microbes. If highly turbid water is the only source available, the suspended solids need to be removed, for example by (cloth) filtration, sedimentation or flocculation. The WATA® is appropriate for urban and rural areas and foster people’s autonomy where the technology is implemented. Since the WATA® devices need a reliable electricity supply to operate, the Mini-WATA®, WATA-Standard® and the WATA-Plus® are designed to be easily powered with solar energy.

Sodium Hypochlorite Production

The user first prepares salt water at 25g NACl/Liter. The WATA® device needs to be immersed in the salt water and connected to a reliable source of electricity. The salt water is converted into sodium hypochlorite solution with a 6 g/L concentration of active chlorine through a process known as electrolysis. Potentially contaminated water can be made potable by adding a small dose of chlorine (5 mL chlorine per 20 L water). Despite the simplicity of operating a WATA® device, the production of active chlorine and disinfection of potable water for a community is a responsibility, and thus requires skilled people as operators, specially trained and dedicated for that purpose.


Production of Chlorine using the WATA-Standard®

Production of Chlorine using the WATA-Standard®

WataTest® and WataBlue® reagents are part of the WATA® kits and allow the user simple onsite water quality control. WataTest® and WataBlue® are non-toxic and inexpensive reagents which are used to measure the active chlorine concentration of sodium hypochlorite and free residual chlorine in the water, respectively. Free residual chlorine (FRC) is important because sufficient levels are required to ensure adequate inactivation of microbes and to guarantee the residual effect that chlorine has of preventing the recontamination of water during handling or consumption. Since increasing levels of FRC makes the water taste and smell unappealing, the WHO recommends a level of FRC between 0.2 and 0.5 ppm in order to strike a balance between disinfection and water taste and smell. 0.5 ppm is the level of FRC that the WHO recommends as striking the balance between effective disinfection and acceptability in terms of taste and smell. The. WataBlue® allows the user to carry out a safe and systematic quality control of the treated drinking water to ensure that this level is reached.

 Tinkisso employees in Guinea, Conakry. Tinkisso produces sodium hypochlorite solution using WATA® devices and then stabilizes and bottles the solution for sale throughout Guinea.

Tinkisso employees in Guinea, Conakry. Tinkisso produces sodium hypochlorite solution using WATA® devices and then stabilizes and bottles the solution for sale throughout Guinea. 


Devices need to be rinsed after each procedure with clean water. If after several uses you notice white marks on the WATA®, prepare a solution of 50% white vinegar (or lemon juice) and 50% clean water. For the Mini-WATA® and WATA-Standard®, leave the device to soak for several hours (overnight for example) and then rinse it with clear water. Never scrub the titanium plates. WATA-Plus®, Midi-WATA® and Maxi-WATA® need to be soaked for at least 24 hours and be completely immersed in the 6 – 10 L solution.


Properly used, well maintained and carefully stored after each use, WATA® devices are designed to operate for 10,000 operating hours, or around 5 years of use. Active chlorine is very sensitive to light. It is therefore very important to store the solution produced with the WATA® devices in closed and opaque, non-metallic recipients and label it with the production date. Place the container in a cool place, out of reach of children. Do not expose it to sunlight. The sodium hypochlorite should be used within 24 hours as the concentration of active chlorine will decline if the solution is not stabilized.

WATA® Application and Business Models

Our objective is to make safe water treatment a profitable activity for communities of developing countries. In the long run, the production and sale of chlorine should create an income generating activity for the local population and ensure their independence in water treatment. The cost for one litre of active chlorine concentrate stands at US$ 0.06.

WATA® is more than a device, it can be combined with health education, technical training, and the creation of an economic model based on sodium hypochlorite and chlorinated water production and sales. Making safe water treatment a profitable activity while insuring autonomy.

Several dissemination models have been tested and approved in the field:

  • Through health centres: The WATA® device can produce, at a very low-cost, the large quantity of quality disinfectant needed to ensure hygiene standards in health facilities. This reduces nosocomial diseases and decreases mortality during childbirth. In addition, the sodium hypochlorite solution can be used as an effective, low-cost wound disinfectant (Dakin’s solution).
  • Through economic structures (i.e. women’s groups, salesperson in kiosks, pharmacies): Direct chlorine sales or disinfection of drinking water, with subsequent sale at kiosks or home delivery, using the chlorine produced by the WATA® device creates an income-generating activity;
  • Through school structures: One WATA® device can ensure that the school’s supply of drinking water is disinfected and be a source of disinfectants to clean floors, surfaces and latrines. They also create an opportunity for promotional and awareness activities around the themes of safe drinking water and sanitation;
  • Through water user associations and water utilities: As an autonomous chlorine generator, the WATA® device can substitute for other chlorinated products in regions where chlorine gases and powders are under embargo, as in armed conflict areas.

To appropriately implement WATA® devices in your specific environment it is recommended to design and test the implementation, pilot it together with the users and customers, adapt and amend the dissemination strategy and the respective business model in order to scale-up and replicate the successful approaches that have been pioneered with the WATA® devices.



  • Local production (avoids most storage and transportation problems and environment impacts)
  • Generation of income for local communities (e.g. water kiosk)
  • Solar versions available for autonomous use
  • Quality control is possible at every stage of production and use
  • Low cost
  • Especially suitable for humanitarian response or war-thorn areas, where for example chlorine gas is banned.
  • Easy to use
  • Disinfectant can be used for a large range of applications (e.g. disinfecting laboratory equipment, wounds, cleaning latrines, disinfecting kitchen utensils and surfaces, washing rough fruits and vegetables etc.)


  • Electricity required (but can be run with solar energy)
  • Education and training for operators are essentials, especially when using Maxi-WATA®
  • Chlorination can cause the generation of a very low concentration of toxic disinfection by-products (DBPs) in the case of disinfecting water with a high organic matter content
  • Dosage might be more difficult than with tablets
  • Only clear water can be used to produce WATA® solution and the solution only effective to treat clean water
  • The device should only be used by a responsible person familiar with the user manual for the relevant WATA® device.
  • Reaction time of 30 min required before consumption after treatment
  • Chlorine taste and smell

References Library

WHO (2017): Safely managed drinking water - thematic report on drinking water 2017. Geneva: World Health Organisation. URL [Accessed: 25.07.2017].

WHO (2016): International Scheme to Evaluate Household Water Treatment Technologies. Geneva: World Health Organisation. URL [Accessed: 07.04.2017].

ANTENNA FOUNDATION (2017): Antenna Foundation – Water & Hygiene. Geneva: Antenna Foundation. URL [Accessed: 10.08.2017].

Further Readings Library

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AUTARCON (2012): AUTARCON SuMeWa System. SolarPV Driven-Drinking Water Treatment. Munich:

Powerpoint presentation of the water purification system implied by AUTARCON. This system uses solar energy to realise mechanical filtration and chlorification of water.

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HEIERLI, U. (2008): Marketing Safe Water Systems: Why it is so hard to get safe water to the poor – and so profitable to sell it to the rich. Bern: Swiss Agency for Development and Cooperation (SDC). URL [Accessed: 07.06.2010].

This book provides unique insights – from the varied perspectives of users, disseminators, producers and retailers – into the marketing challenges of point-of-use water treatment devices.

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UNICEF (Editor) (2008): Promotion of household water treatment and safe storage in UNICEF WASH programmes. pdf presentation. New York: United Nations Children's Fund. URL [Accessed: 17.03.2010].

Short introduction to household water treatment and the main treatment methods.

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CDC/USAID (Editor) (2008): Preventing Diarrhoeal Disease in Developing Countries: Proven Household Water Treatment Options. Atlanta and New York: Center for Disease Control and Prevention (CDC) and United States Agency for International Development (USAID). URL [Accessed: 15.03.2010].

One-page introduction to main household water treatments methods, and further reading links.

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CDC/USAID (Editor) (2009): Filtration & Chlorination Systems . (= CDC Household Water Treatment Options in Developing Countries Factsheets). New York: Center for Disease Control and Prevention (CDC) and United States Agency for International Development (USAID). URL [Accessed: 01.04.2010].

Introduction to filtration and chlorination systems at the household level.

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CLASEN, T.D. (2009): Scaling Up Household Water Treatment Among Low-Income Populations. (PhD Thesis). Geneva: World Health Organization (WHO). URL [Accessed: 09.04.2010].

This report examines the evidence to date regarding the scalability of HWTS. It seeks to consolidate existing knowledge and experience and distil the lessons learnt. Its primary aims are to 1) review the development and evolution of leading household water treatment technologies in their efforts to achieve scale, 2) identify the main constraints that they have encountered and 3) recommend ways forward.

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IFRC (Editor) (2008): Household water treatment and safe storage in emergencies. pdf presentation. Geneva: International Federation of Red Cross and Red Crescent Societies (IFRC). URL [Accessed: 23.04.2012].

This document is intended as a general manual on household water treatment and storage in emergencies. Methods of treatment but also promotion are presented, including factsheets, a decision tree and very comprehensive illustrations.

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NWP (Editor) (2010): Smart Disinfection Solutions. Examples of small-scale disinfection products for safe drinking water. (= Smart water solutions). Amsterdam: KIT Publishers. URL [Accessed: 07.07.2010].

This booklet, part of the Smart Water Solutions series provides a wide range of methods and products for home water treatment in rural areas.

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WADDINGTON, H.; SNILSTEIT, B.; WHITE, H.; FEWTRELL, L. (2009): Water, sanitation and Hygiene interventions to combat childhood diarrhoea in developing countries. (= Synthetic review, 001). New Delhi: International initiative for Impact Evaluation (3IE). URL [Accessed: 07.06.2010].

This document provides a review of the effectiveness of interventions in the water, sanitation and hygiene (WASH) sector in promoting better health outcomes in developing countries, as measured by the incidence of diarrhoea among children.

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WHO (Editor) (2011): Guidelines for Drinking-water Quality, Fourth Edition. Geneva: World Health Organization (WHO) . URL [Accessed: 08.08.2011].

This volume of the Guidelines for Drinking-water Quality explains requirements to ensure drinking-water safety, including minimum procedures and specific guideline values, and how those requirements are intended to be used. The volume also describes the approaches used in deriving the guidelines, including guideline values. It includes fact sheets on significant microbial and chemical hazards.

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WORLD CHLORINE COUNCIL (Editor) (2008): Drinking water chlorination. Position Paper. URL [Accessed: 07.06.2010].

This 8-pages information paper highlights chlorine’s critical role in providing safe drinking water; the potential health and environmental effects of chlorine and disinfection by-products; and considerations for selecting disinfection methods.

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DESILLE, D. (2013): Conservation et Traitement de l Eau a Domicile. Paris: Programme Solidarite Eau (PSeau). URL [Accessed: 06.06.2013].

This practical guide provides a review of different processing techniques and adequate water conservation at home and is structured around 10 key questions that should be posed before choosing a suitable solution.

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ANTENNA FOUNDATION (2017): Antenna Foundation – Water & Hygiene. Geneva: Antenna Foundation. URL [Accessed: 10.08.2017].

Antenna Foundation, a Geneva-based Swiss Foundation dedicated to develop and disseminate technologies for essential needs of the most vulnerable people around the world, presents its activities including the WATA® devices and provides the reader with background information about safe water and hygiene.

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ANTENNA FOUNDATION (2017): Range of WATA® Devices. Geneva: Antenna Foundation. URL [Accessed: 10.08.2017].

The instruction sheet provides detailed information of how to install and use the WATA® devices in different contexts. It highlights precautions to be made and provides additional information about the production and use of sodium hypochlorite.

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ANTENNA FOUNDATION (2017): Range of WATA® Devices - FAQ. Geneva: Antenna Foundation. URL [Accessed: 10.08.2017].

This link presents the frequently asked questions (FAQs) and answers on the installation, use and maintenance of WATA® devices as well as the different applications of active chlorine. It has been prepared and complied by Antenna Foundation.

Case Studies Library

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SOBSEY, M.D.; HANDZEL, T.; VENCZEL L. (2003): Chlorination and safe storage of household drinking water in developing countries to reduce waterborne disease. In: Water Science and Technology 47, 221-228. URL [Accessed: 07.06.2010].

This study evaluated point-of-use chlorination and storage in special plastic containers of gathered household water for improving microbial quality and reducing diarrhoeal incidences among consumers living under conditions of poor sanitation and hygiene.

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WIDMAN, M. (2011): PV Meets Drinking Water. In: pv magazine 12. URL [Accessed: 16.07.2012].

This article describes the practicability of a water purification system which is not reliant on batteries but on solar radiation.

Important Weblinks

http://www.unicef.org/wcaro/2009_4073.html [Accessed: 01.07.2010]

In response to a severe cholera outbreak in 2006, UNICEF has partnered with Tinkisso, a local NGO in the region of Dabola that produces active chlorine with WATA devices.

http://www.humanitarianreform.org/Default.aspx?tabid=343 [Accessed: 01.07.2010]

A complete WASH Cluster Hygiene Promotion training package.

http://www.pedag-eau.fr/ [Accessed: 01.07.2010]

Awareness raising material on water, sanitation and hygiene (only available in French).

http://www.antenna.ch/en/drinking_water/wata_guides.html [Accessed: 01.07.2010]

User guide for WATA kit and quality control reagents.

http://www.youtube.com/ [Accessed: 01.07.2010]

This video explains how to produce active chlorine with WATA devices. FRENCH

http://www.youtube.com/ [Accessed: 01.07.2010]

This video explains how to use active chlorine produced with the WATA device for drinking water, disinfection and cleaning. It explains also how to use the tests to control disinfection and residual chlorine concentrations. FRENCH

http://www.antenna.ch/en/drinking-water.html [Accessed: 01.07.2010]

This website provides general information on chlorine and its different uses, WATA devices (user guides) and quality control reagents as well as on the WATASOL approach and its implementation around the world.

http://www.antenna.ch/en/drinking_water/wata_press.html [Accessed: 08.06.2010]

This internet link presents the WATA press release and various articles on WATA and the WATASOL approach.

http://www.akvo.org/wiki/index.php/WATAsol [Accessed: 01.07.2010]

Akvopedia is an open water and sanitation resource and provide information on production of active chlorine with WATA devices.

http://www.eaudejavel.fr/pages/eau/chimie.asp [Accessed: 01.07.2010]

This website in French is a host of information on chlorine. FRENCH

www.cdc.gov/safewater/about_pages/chlorinationtable.htm [Accessed: 01.07.2010]

This site describes the effect of chlorination on inactivating selected pathogens.

http://300in6.org/ [Accessed: 01.07.2010]

300in6 is an initiative to provide 300 million people with safe drinking water in 6 years with a focus on home water treatment options that include chorine.

www.antenna.ch/en/water-hygiene/ [Accessed: 25.07.2017]

Quick overview of the WATA® approach

www.antenna.ch/en/water-hygiene/range-wata/ [Accessed: 25.07.2017]

Full range of WATA® devices are presented under this link. The different performances of the chlorinating devices are highlighted and applicability emphasized.


The blog entry describes a 3-year safe water initiative led by Antenna Foundation to facilitate market based business approaches in safe water that do partly build around the application of WATA® devices.


Short video about the WATA® device and its positive health impact for people when treating water consistently. Produced by Antenna Foundation on the occasion of World Water Day 2017.

youtube.com [Accessed: 25.07.2017]

Short video describes Antenna Foundation’s core approach of scientific resarch of technological, health and economic solutions to meet essential needs of marginalized populations around the globe.