“Cool Foam”: How Constraint Yields Novelty

Anyone lucky enough to live in a place where sinks are prevalent and running water is reliable scarcely thinks about the simple task of washing their hands. But handwashing is not something to take for granted: it is a task that requires considerable planning for billions of people around the world who lack access to adequate sanitation and piped water.

Handwashing, whether in piped or unpiped communities, saves millions of lives every year. Good hand hygiene is a highly effective weapon against diarrhea and respiratory illness, both of which are leading causes of childhood death. The American Journal of Public Health estimates that handwashing with soap can reduce acute respiratory infections by 21 percent and the risk of diarrhea by 40 percent; USAID estimates that handwashing with soap could save a million lives a year.

Yet, according to the WHO, 43 percent of the global population does not have easy access to piped water, which puts them at a higher risk for health problems, partly because of the logistical challenge of handwashing.

Handwashing with soap could potentially save a million lives a year.

The U.N. is trying to improve access to clean water and sanitation through its Sustainable Development Goals for 2030, which calls for adequate and equitable sanitation and hygiene for all, including “hand-washing [facilities] with soap and water.” Installing plumbing in every home and community is not a feasible way to reach this goal, however, so most efforts focus on effective handwashing without piped water. A simple basin and bar of soap is sufficient, if it is managed well, but that means always having an available stock of clean water and soap; ensuring that the water is not contaminated from multiple washes; and draining the soap and water runoff appropriately.

That sounds easy until one considers the time and labor intensity of keeping a supply of fresh water in households without plumbing. In sub-Saharan Africa alone, two-thirds of the population has to leave their homes to fetch water for household use—a responsibility that falls disproportionately on women and children. Indeed, 17 million women and children across the continent spend 30 minutes or more each day collecting water, according to research published last year in PLOS One, an open access journal.

Maintaining a stock of soap can be equally challenging, because in many low-income areas, soap is prone to theft. “Soap is a borderline luxury good, so not all households have it. A family has to make a decision about whether to spend money on it,” explains Rachel Steinacher, a research manager for Innovations for Poverty Action (IPA), a non-profit health research organization. “If schools’ don’t lock down their soap, kids will take it,” she adds.

Needless to say, the basin-and-soap option often fails to be an effective handwashing option. There are other hardware options for unpiped handwashing, but they fall far short of serving the billions of people worldwide without access to piped water and their varying living circumstances, preferences and constraints. Affordability, durability, security, and accessibility of materials are the biggest challenges to developing hygenic and effective unpiped handwashing hardware.

Dissecting design


These issues unwittingly came to the fore during a hygiene study in Kenya undertaken by IPA. The organization’s stated mission is to turn “high-quality evidence” into better programs and policies for the poor. It also provides technical assistance to apply solutions at scale. In 2011, IPA was tasked with collecting data about the impacts of handwashing on child health and development as part of a larger research initiative called the WASH Benefits study, backed by the Bill & Melinda Gates Foundation. The overall study focused on the relationship between access to hygiene tools—such as handwashing stations, and trays and sweepers for cleaning areas where open defecation is practiced—and nutrition. IPA’s specific portion of the study, which was funded by USAID, involved designing, installing and monitoring unpiped handwashing stations in Kenya’s Western Province, says Steinacher.

“The objective was to [make] handwashing with soap and water more convenient in settings with limited water supplies,” adds Amy Pickering, an assistant professor in environmental health at Tufts University and principle investigator for IPA.

IPA began its research by donating a product it had developed several years earlier to the communities participating in the research. The device, called the “dual tippy tap” is comprised of a couple of jerricans mounted on a metal stand in the ground. One of the containers holds soapy water and the other holds plain water. Each can be tipped by a simple foot-powered mechanism, so that soapy water or rinsing water trickles onto users’ hands. IPA’s team went village to village to install the devices, inviting villagers to watch the installation process and explaining proper usage and benefits. The villagers agreed to use the tippy taps for the duration of the two-year trial.

Problems with the tippy taps began to materialize quickly, however. For one, they were less durable than anticipated: rusting was common, and sun exposure caused the ropes and jerricans to degrade. Also, children found the devices difficult to use when they were heavy with water and often used the structures as play areas, sometimes damaging the tippy taps. There were a host of other issues as well: sharp points on the structures periodically cut users hands; the ground beneath the structures was prone to mud; it was sometimes hard to tell which container held water and which held soap; and parts would get stolen because the devices were not portable, so they could not be put inside at night for safe keeping. Within 18 months, most of the devices fell into disuse.

IPA changed course: it decided on a complete redesign of the handwashing station. But while the organization had specialists on research and behavior change, they did not have in-house product development experts to explore and iterate hardware solutions. They thus partnered with non-profit design firm Catapult Design, which had experience prototyping in East Africa, as well as design and manufacturing networks.

A tall order

When Catapult Design joined the project, IPA outlined an ambitious set of design constraints that reflected their overall project brief. “We wanted to design a product that was very efficient in using soap and water for handwashing, [which would] reduce the cost of purchasing soap and water, and which was also part of an integrated system to make handwashing convenient,” Pickering says. More specifically, the hardware would need to be adaptable, so that it could be configured to the specific needs of a wide variety of unpiped users, from households to schools to health clinics. To address security issues, the system would need to be portable and have an integrated soap feature—IPA did not want the device to rely on padlocks, where keys could be lost or locks could rust. The device would have to be able to accommodate different types of soap (bars, liquids, and powders) since no one type was universally available. And lastly, the final price could not exceed US$12.

Highly specific project briefs sometimes make assumptions about user needs, which goes against best practice in human-centered design. But having a clear agenda and focused budget can help balance ideals with constraints.

IPA’s highly specific project brief would not be an ideal starting point in many frugal design projects. For one, briefs with many constraints sometimes make assumptions about the needs of their target users, and approaching target uses with established preconceptions of a solution generally goes against best practice in human-centered design. But for IPA, having a clear agenda and focused budget helped balance ideals with constraints. It also narrowed the technology options that might be a good fit for its study.

In August 2013, with the project brief in hand, Catapult’s product design team started on the first of three month-long field visits to Kisumu. The goal of the trip was to understand why the Tippy Taps were not up to task. Catapult held focus groups alongside the IPA behavior team in the Kisumu communities, visiting a health clinic, a dispensary, and a primary school to learn about institutional handwashing and water-access conditions. The team also visited households on both from both the control and intervention sides of the Tippy Tap study. Through interviews and other exercises, like illustrated card sorting, Catapult and IPA observed hygiene-related behaviors and learned about users’ habits and preferences. Finally, they visited local kiosks, shops, and hardware stores to discover what other products were available in the market. The trip concluded with a local stakeholder workshop to take questions and suggestions.

The initial visit gave the team enough customer and hardware insights to begin exploring product concepts and prototyping. It also allowed IPA and Catapult to identify participant groups for the eventual product pilot. These included three schools, two clinics, and five households. On the two subsequent visits, Catapult worked with local materials and fabricators to build design prototypes and held weekly feedback visits for its prototype designs with each of the ten participants; the team attempted to incorporate that feedback in time for the following week’s visit. IPA’s behavior change team also offered feedback on Catapult’s early designs, especially on water and soap management and hardware maintenance.

User preferences

Several recurring themes in user feedback surfaced throughout the multi-stage design and testing process: device affordability, device adaptability, and soap security. During the early interview period, users shared their frustration with the Tippy Taps’ poor structural integrity; many also said the overall design was not enjoyable or easy to use, particularly the soapy water container. Then, as Catapult began testing various design ideas, specific user preferences surfaced. For instance, many wanted control over the on-off function of the tap, rather than using automatic taps, which users found irritating. Although it is labor intensive to fetch water for unpiped hygiene use, tap control overrode concerns that the tap would be left open, draining the water supply.

To cover its bases, Catapult and IPA reviewed the range of unpiped handwashing technologies available globally and in Kenya, before embarking on their own product design. “We wanted to review all types of handwashing stations available in Kenya, and look at their advantages and disadvantages,” says Pickering. There were plenty of products designed for unpiped use at various stages of market readiness; none met all of the requirements of the IPA project brief, however. A few such examples include:

  • The Labobo Happy Tap—a 10-liter device that is easily transported, refilled and distributed. It includes a simple, user-controlled tap, but the soap feature—either a bar or separate pump—cannot be secured to the device, which means the soap can be easily stolen.

  • Oxfam’s specialty tap and bucket, with a sealable lid. The product is mass produced for emergency relief purposes. It also does not have an integrated soap feature, however.

  • Polytanks’ line of handwashing products, starting as small as 20 liters. The Nairobi-based plastics manufacturer designed the line for institutions and sells the products as scale. None of the products were close to IPA’s target cost or water flow rate, however, and again, none had an integrated soap feature.

These and other products offered IPA and Catapult design inspiration. Features from Sustainable Sanitation Alliance’s simple hanging bucket with push-activated tap and the design configuration of Portland, Ore.-based Public Hygiene Lets Us Stay Human’s (PHLUSH) unpiped handwashing product were adapted for Catapult and IPA’s final product design, for example. But it became clear through their product review that Catapult and IPA would have to undertake a lot of original design, particularly around a built-in soap feature.


The soap feature was in fact the most challenging element to design, says Pickering, and not just from the security standpoint. The relatively high cost of soap in many unpiped communities is one of the biggest roadblocks to sustained handwashing behavior. The team was therefore motivated to explore soap solutions that “stretched” small amounts of soap for as many handwashing uses as possible.

Catapult came up with a simple idea to the soap economy problem: foam soap that could be made from bar, liquid, or powdered soap. The device Catapult designed to make the foam was also exceedingly simple: a soft plastic accordion-style container, a synthetic fabric wick, and a hard plastic nozzle. Users place one cap of powdered or liquid soap or a small piece of bar soap in the accordion container along with 250ml of water. When the accordion is suppressed, the air in the wick mixes with the soap and water and dispenses foam onto users’ hands.

To the residents of Kisumu, foam soap was a novelty—something most had never seen or used before. The new local form of soap became inspiration for the handwashing station name: the “Povu Poa,” which means “cool foam” in Swahili.

The Povu Poa’s economical use of soap may have been the biggest gain of the project, Pickering says. “The [soap] dispenser can convert five grams of regular powered laundry detergent and [250ml] of water into enough foam for 100 hand washes,” Pickering says. That made the product more affordable than any other soap option, especially off-the-shelf foamers, which have more complicated configurations and parts. The Povu Poa also uses 94 to 99 percent less soap than other handwashing systems available in the local market, providing approximately 15,000 handwashes per $1 of soap compared to as few as 500 handwashes with conventional systems. Overall, the cost of soap and water for the Povu Poa is less than $0.10 per 100 uses, compared with $0.20 to $0.44 per 100 uses for other systems.


Sleek, frugal and secure

For the Povu Poa’s overall design, Catapult developed two different configurations to cater to household and institutional needs: a 5L vertical pipe-shaped system and a 20L bucket-over-bucket system. For the latter, “two buckets are placed vertically with a connection piece between them,” Pickering explains. The smaller system holds enough water for approximately 14 handwashes between refills, while the larger system can be used for up to 60 handwashes. “The pipe model has a smaller capacity, but it is more flexible in design and can be plumbed to larger water storage tanks if desired,” Pickering adds.

While the two Povu Poa systems are different in appearance and capacity, both are built with a water-frugal tap and interlocking soap dispenser to minimize the risk of soap theft. The tap swings multi-directionally and can be easily activated with the back of the hand, wrist or knuckles, like medical handwashing sinks. It was designed to produce minimal water flow—barely more than a trickle—because IPA and Catapult’s research revealed that effective handwashing actually requires very little water. Also, a low-flow system helps ensure that the water supply is used for handwashing, rather than other uses, like dishwashing or cooking.

To address security concerns, both Povu Poas were designed to be portable, so they can be stored inside to prevent theft or vandalism. Catapult also designed parts like the tap and soap dispenser to require disassembly to remove; making the tap and soap container annoying to dismantle was the best defense that the team could achieve within the $10 to $12 price target of the brief. The added costs of maximizing the system’s security would have made the product unaffordable or too expensive to replace if something did happen.

Cost was a constant limitation throughout the project’s design process, owing to the limited financial resources of the study’s target users. As a research organization, IPA never intended to manufacture and sell the product it was working on in the study, but it wanted to lay the groundwork for another organization to take the Povu Poa to market in the event that it was successful in field trials. IPA therefore conducted a “willingness to pay” study once Catapult had refined the models to the point that a few hundred units could be produced.

Foam soap was not only cost effective, it was a novel new kind of soap in Kisumu.

“We held community meetings to determine households’ level of interest in buying the Povu Poas. Those who expressed interest—about 80—were enrolled in the [willingness to pay] study,” Steinacher explains. IPA then went door-to-door to sell the 5L pipe model, randomly assigning subsidies to different households. Some were offered the device at “full” price: 1,200 Kenyan shillings (KES), or $12. Others were offered the device at KES800 and KES400 price points. The households were given the chance to buy the product on the spot, or not at all. Less than 10 percent of the 1,200KES households accepted the offer, but 35 percent of the 800KES households and 80 percent of the 400KES households did. Steinacher says the team was pleasantly surprised by the uptake.

“That’s pretty high. People don’t have a lot of cash on hand to make a split-decision [purchase],” she says. “It’s tantalizing in terms of what sales could be if Povu Poas were sold in a store, or with backing from a microfinance institution.” Either option would allow families to save for the product, which might a KES1,200 price tag more feasible. Steinacher says the figure was just an approximation of how much the small Povu Poa would cost to manufacture. “Comparatively, KES1,200 is pretty low-cost. Tippy taps are not that cheap. Other NGOs are paying $40 for really basic handwashing stations,” she adds.

It has now been more than three years since the Povu Poa design and field testing project in Kisumu, and roughly 200 of the product prototypes are in circulation in the communities there. Since then, IPA has been in discussions with for-profit companies to try to push the commercialization of the Povu Poa forward. “We have gotten so much interest—people [in Kisumu] asking us if it’s ready for sale. So many teachers [have been] asking when they can buy it,” Steinacher says.

Retail Povu Poas are still at least a couple years away, which is arguably unfair, on some level, to the people in IPA’s partnering communities who have worked diligently with IPA to identify and create a suitable product for their needs. Steinacher says that as a research organization, IPA is simply not equipped to deliver products to market; however, it is gearing up for a new study with the device in Tanzania and is hoping to partner with a large-scale manufacturer to push it in that direction.

In the meantime, the 200 devices in circulation in Kisumu are serving more than their purpose as effective stations for families to wash their hands. “Households are excited to [display] it in their living rooms,” says Pickering. Adds Steinacher, “I was really struck by how proud people are of their Povu Poas. It has become a centerpiece in their homes.”

Written by Noel Wilson, creative director of Catapult Design, with reporting by Adrienne Day, a Demand contributing editor.