Handwashing With a Water-Efficient Tap and Low-Cost Foaming Soap: The Povu Poa “Cool Foam” System in Kenya

The new handwashing system, designed with end user input, features an economical foaming soap dispenser and a hygienic, water-efficient tap for use in household and institutional settings that lack reliable access to piped water. Cost of the soap and water needed for use is less than US$0.10 per 100 handwash uses, compared with US$0.20–$0.44 for conventional handwashing stations used in Kenya.


BACKGROUND
Handwashing with soap and water reduces the spread of respiratory and diarrheal disease, the 2 leading causes of death in children under 5 years old. [1][2][3][4][5] Studies estimate that handwashing with soap can reduce acute respiratory infections by 21% and the risk of diarrhea by 40%. 6,7 In settings without piped water, refilling water containers and securing soap for handwashing requires constant user effort and expense, creating barriers to handwashing with soap. In Kenya, for example, 78% of the population lacks access to household piped water, 8 and the prevalence of handwashing with soap after contact with feces is estimated to be 15%. 6 People are more likely to wash their hands at critical times if they have a dedicated place with soap and water. 9 Conventional handwashing stations in Kenya, such as a jug and basin ( Figure 1A) or a bucket with a tap ( Figure 1B), are prone to soap theft, are cumbersome and unhygienic, and are not water-efficient. Alternative handwashing systems aim to provide affordable, water-efficient, and dedicated locations for handwashing. For example, the ''leaky tin'' dispenses water from a hole near the base of a container when a person removes a plug, and the ''tippy tap'' dispenses water by tipping the container when a person pulls on the attached string lever or steps on a foot pedal. However, difficulties with soap provision and security remain. The dual tippy tap integrates separate containers for soapy water and rinse water into a single system to address these issues ( Figure 1C). 10 The soapy water mixture, a 50:1 water-to-powdered soap ratio, increases the lifetime of the soap and is an effective cleansing agent. 11 Still, the dual tippy tap has several shortcomings: it can become unstable over time, it requires frequent maintenance, the metal components are prone to theft, and the hardware is not particularly attractive.

INNOVATION PROCESS
We began our design process by conducting in-depth interviews and focus group discussions with potential users in low-income, peri-urban areas of Kisumu, including household members in 5 households, students and teachers in 3 primary schools, and health care workers in 2 clinics. Users preferred hand washing systems that were easy to operate and refill with water, a tap that allowed them to control the flow of water, and a portable unit that they could store inside their home or institutions at night to prevent theft. We then created a series of handwashing system prototypes in response to user needs and iteratively developed the designs with multiple rounds of input from end users based on their experiences testing the various features.
After multiple rounds of user-focused testing with various handwashing components and systems, the final product we developed was a desirable, robust, affordable, and water-frugal system that integrates a secure soap dispenser with rinse water. We developed 2 configurations of the system, both of which are currently marketed under the brand Povu Poa (''Cool Foam'' in Swahili).
The Povu Poa bucket model is composed of two 20-liter buckets stacked vertically, which can be set on any level surface and easily disassembled for transport and security ( Figure 2A). The Povu Poa pipe model is a light, highly portable 5-liter pipe that can be hung from a wall, fencepost, tree, or other standing structure and that can be plumbed to larger water tanks and drainage systems ( Figure 2B).
Both Povu Poa models integrate the waterfrugal swing tap to dispense water ( Figure 3A) and the accordion soap foamer that mixes soapy water with air to create a foam ( Figure 3B). Runoff water from handwashing collects in the lower bucket for the bucket model or a separate basin for the pipe model (not shown).

KEY PRODUCT FEATURES OF THE POVU POA HANDWASHING SYSTEM
Soap security: The soap foamer is attached to the system, preventing theft. Affordability: Just 5 g of powdered or liquid soap mixed with 250 mL of water can provide 100 uses for US$0.10 (cost includes soap and water). Hygienic: The innovative swing-tap design is bidirectional and can be used with the back of the hand or wrist, limiting recontamination of hands after handwashing. Water-frugality: The water flow is sufficient for handwashing while providing a 30-77% reduction in water usage compared with conventional methods. Scalability: Components are specifically designed for low-cost mass production and deployment, estimated at US$12 per unit. Adaptable: The 2 handwashing station configurations can be adapted to meet different 78% of the population in Kenya lacks access to household piped water, creating barriers to handwashing with soap.
The handwashing system we developed, marketed under the brand Povu Poa, comes in 2 configurations: a bucket and a pipe model. needs and preferences ( Figure 4) and can be used in households and institutional settings, such as schools and health centers.

SOAP AND WATER EFFICIENCY TESTING
We tested the water and the soap efficiency of the Povu Poa pipe and bucket prototypes alongside 6 handwashing systems commonly used in Kenya, such as the dual tippy tap and a jug and basin. At the beginning of each test, the system being evaluated was filled to capacity with water. For each test, research assistants from Innovations for Poverty Action washed their hands with soap and water for 20 seconds. Handwashing events continued intermittently until the water reservoir was empty. The total volume of water and handwash count were used to calculate water quantity per use. Before and after weights of the soap were used to calculate the amount of soap per use. Actual soap costs were used along with user-provided water prices.
The Povu Poa systems used 30% to 77% less water compared with the conventional systems tested, providing approximately 14 to 15 uses per 5 liters of water compared with 4 to 10 uses from the other systems (Table). The Povu Poa systems also used 94% to 99% less soap than the other tested systems, providing approximately 15,000 uses per US$1 spent on soap compared with approximately 500 to 1,600 uses with conventional systems. Overall the cost for soap and water with the Povu Poa is less than US$0.10 per 100 uses, compared with US$0.20 to US$0.44 per 100 uses for other systems tested. The waterfrugal tap provides approximately 60 and 14 uses between refills for the bucket and pipe model, respectively.
Based on these results and our estimated mass production cost of US$12 for the Povu Poa pipe model, the pipe model would pay for itself in approximately 2.5 years for a family of 5 who each wash their hands 3 times per day using a jug and basin. When considering the soap foamer alone, at a mass production price of US$3, the

CURRENT AND FUTURE WORK
In focus group discussions, approximately 80% of participants stated they would purchase a Povu Poa product, suggesting the aspirational value of the product. We have produced 200 Povu Poa systems in Kenya and are currently field testing them in peri-urban households, schools, and health clinics to assess long-term usage (up to 1 year of evaluation) and durability. To assess demand for the product, Povu Poa units are currently being sold to households at randomized price points, ranging from US$1 to US$12, to determine the price that most low-income users are willing and able to pay. Next steps include finalizing the design for mass production of the Povu Poa system, partnering with a plastics manufacturer, and identifying effective sales and distribution strategies.