Water purification design for Hippo Rollers wins awards

Matthew Baharmast and Patrick Berry

Share This Post


It was in early October  2016, that the Hippo Roller team received an email from a young high school student in the US. Matthew Baharmast and his partner Patrick Berry of Madison High School, were working on a science project, trying to come up with a water purification design for the Hippo Roller.

“I am working on a science project related to Hippo Rollers. Can you tell me where I might be able to buy one/get one in the US. I live in Northern Virginia (near Washington, DC).”

This is the kind of thinking that creates better solutions, and we were only too keen to assist. Within weeks Matthew had a Hippo Roller in hand, and had started working on a UV lighting water purification solution and some method of powering it through the motion of the moving Hippo Roller.

Their thinking was that whilst the Hippo Rollers are a brilliant means of transporting water long distances by foot, “what if that energy could be harnessed at the same time to help purify the water.”

The concept is that on the way to the water source, the rolling drum would charge the batteries, so that on the way back home, the batteries can be used in the UV-C lights to sanitise the water. This creates a self-sustaining water purification system.

Access to clean water

Hippo Roller reached out to Matthew and his lab partner, Patrick, to ask him a few questions about the project.

[Hippo Roller] What got you thinking about the problem of water quality?

[Matthew Baharmast] We had read about the lack of sanitary water in developing countries and were already aware of organisations such as Hippo Roller. In our research, we found that nearly one out of every four people on the African continent did not have access to clean drinking water nearby, and we decided we needed to figure out a way to find a solution to the issue.

[HR] How did you come to select the Hippo Roller as a test bed and vehicle for your research?

[MB} We had read about the Hippo Roller, and we thought it would be great if we could come up with a simple, cost-effective addition to help purify the water it transported. Since Hippo Rollers are already being manufactured and distributed, we thought that it would be best to build off of the already established product.

[HR] And we’re delighted that you did. Knowing that the Hippo Roller has been benefiting 100s of thousands of people, what were your impressions when you took delivery of it?

[MB] It is amazing to think that such a basic concept is saving lives all around the world. We also thought that its simplicity could lend itself to modification and adaptation for different purposes such as our water sanitation attachment.

[HR] Could you provide any specifics on exactly what you did, what equipment was used and how it was applied?

[MB] We equipped the Hippo Roller with a low-cost, conventional bicycle dynamo attachment that generated power from the rolling of the drum. The energy from the dynamo was then used to a power battery charger; the rechargeable batteries were then were placed into portable UV-C lights inside of the drum.

The concept is that on the way to the water source, the rolling drum would charge the batteries, so that on the way back home, the batteries can be used in the UV-C lights to sanitise the water. This creates a self-sustaining water purification system.

UV water purifier prototype
A prototype Hippo Roller UV water purification solution

[HR] Such a simple solution! Have you given any thoughts as to the potential commercialisation of your idea ie: Hippo Roller UV Water Purification?

[MB] It definitely has the potential of being commercialised, but it would require somewhat better engineering. Instead of the dynamo powering batteries to be placed in the lights, our plan for a future model would have the dynamo connected directly to the lights inside of the drum itself.

This could make our device more efficient and potentially even make it kill more bacteria and protists in the water.

Our design was also very affordable which would be perfect for commercialisation. The supplies for our rig should cost USD20 or less wholesale, which would make it practical to be distributed with Hippo Rollers.

[HR] The simplicity of the Hippo Roller is its biggest asset in tough, rural environment. Do you think your idea can be engineered in a simple way to making it practical and cost-effective in the same harsh conditions?

[MB] Yes, definitely. We were thinking about making this an affordable, durable water purification system that fit in well with the Hippo Roller concept.  If you think about how simple and practical a bicycle dynamo is; this is basically just an extension of that. The UV-C water purification idea really requires nothing more than the dynamo itself to generate power and does not impede the water transport in any way.  I see this concept being a very practical solution to the global clean-water crisis.

The results

Whilst the Hippo Roller is brilliant in its ‘last mile’ role transporting water, the water drawn from distant sources is often unsanitary and dangerous if immediately consumed. Boiling water to make it safe for drinking is easier said than done when you spend three to nine hours a day fetching that water, and fuel for fires is carefully rationed.

Said Matthew, “In our experiment, we used a self-sufficient UV light in a Hippo Roller to attempt to sanitise water. We tested the effect of UV light over time and set distances on bacteria and protozoa in water.”

“We used a consistent measure of bacteria and protozoa in each sample of water, inserting our UV light into the drum, pushing it at a constant speed, and then testing the water at half-mile (one km) increments.”

Said Matthew, ‘Our results showed that as we pushed the barrel longer, more bacteria and protists were killed, as we thought would be the case. Our experiment was successful in verifying that almost all living particles in the water were neutralised in every trial at the lower range of average water hauls (approx. 2 miles/3 km).”


  • The project won first place in the microbiology category of the Fairfax County science fair and an Honorable Mention Award for the Virginia State Fair.
  • Honorable Mention at the 2017 Virginia State Science and Engineering Fair were presented to Matthew Baharmast and Patrick Berry of Madison High School (Effect of UV Light on Bacteria and Protist Levels in Drinking Water) and second place from the Virginia Section of the American Water Works Association.
  • Microbiology, honorable mention; Virginia Section of the American Water Works Association, second – Matthew Baharmast and Patrick Berry, “Effect of UV Light on Bacteria and Protist Levels in Drinking Water,” James Madison High School
  • Certificate of Merit: American Industrial Hygiene Association
  • Certificate of Merit: American Water Works Association, Virginia Section
  • Cash award: American Society for Microbiology, Washington DC
  • Source: https://www.fcps.edu/node/33195
Featured image: Matthew and Patrick testing the effect of UV light on bacteria and protist levels in drinking water.

More To Explore