Water Hippo Hack

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Gathering Materials & Beginning Prototype Construction
Born On:
19:26, 29 August 2010 (CDT)
Last Updated:
10:13, 23 November 2010 (CDT)


This page is for members who are working on the collaboration project with Engineers Without Borders - UAH (EWB-UAH Google Group). We are working on the development of a low-cost alternative to the water hippo using appropriate technologies for the rural African environment of Zambia as well as local resources and labor for production to support the local economy. The Water Hippo is a device meant to ease water transportation in rural areas where locals use traditional methods of water transport.


To Dos

  1. Complete First Water Hippo Hack Prototype by 12/18.


  • 11/13/10 - Opticron came up with the idea to use a pulley system to yoke the water barrel; a belt loop would run over the center of the barrel on one end of the pulley and a small spool and lubricated dowel on the other. That way, it could be pulled by at least two people on each ends of the dowel and there would be no need to modify the barrel caps to accommodate a yoke. Good one, Opticron! Preauxphoto also made mention that for water purification, one could either drop some bleach into the water before rolling it home, let it sit open overnight to vaporize the chlorine and remaining bleach and then boil. Alternatively, a cloth bag with charcoal could be dropped into the barrel and allowed to form a beneficial biofilm to filter the water. The agitation of transport would allow for the water to pass through the filter sufficiently. However, it would still need to be boiled. Spacefelix started cutting the range rover tires with a hacksaw to sleeve them over the barrels. It is of note that there are steel belts in the tire on its edge and on the inner ring where it meets the wheel. Therefore, the best method of cutting involves puncturing the unreinforced sidewall of the tire until a slit long enough to insert a cutting saw is made. Hand cutting it not difficult as the sidewall is all rubber. On Weight limits, assuming that the barrel only needs half of its weight in pulling force to roll over ground and a person can only exert their weight in force, we are looking at needing at least three fully-grown men to haul the current 55 gallon hacked water hippo (~470 lbs).
  • 10/10 - Have gathered materials for the Water Hippo Hack Project. Preauxphoto gave some advice on strcutural integrity and the concept was revised from the original tires-on-end to tires-over-barrel-bands to make it more structurally sound. Wooden inserts will be placed in the tires to give them shape and structure. Need to resolve issue of yoking. Also, there is the issue of weight; the 23-gallon water hippo roller would weigh in at ~200 lbs, but the 55 gallon concept device will be ~470 lbs when fully loaded. Need to determine reasonable weight and pulling force limits.
  • 9/3/10 - Got some information from EWB on materials available in the Zambia Project as well as a design concept to prototype. Right now, the EWB team would like to prototype with the Makers a version akin to the Recycled Water Hippo that utilizes a 55-gallon plastic barrel capped with old tires. The tires would be spoked by 2x4s in a cross with the intersection at the rolling axis of the barrel to provide a point to attach a pulling/pushing mechanism. To retain the tires to the ends of the barrel ropes would be strung from one wheel's spokes to the other. EWB member Justin Wetherwax will be bringing in some old tires before 9/17. Spacefelix will find a 55-gallon plastic barrel from the car washes on University (per Ratmandu) by then. We are looking at having a basic prototype done by 10/1.
  • 8/20/10 - EWB and the Makers have started collaboration on the project. Discussed with the Makers on concepts for the water hippo hack.

Design Considerations

  • Materials & Labor Available
    • 55-gallon plastic barrels
    • Old Range Rover Tires
    • Wood 2x4s
    • Basic Hand Tools and Fasteners such as wood spikes.
    • Basic Shopwork Knowledge
    • The pulling force of either a woman or child. <- Assuming that a water roller needs half its weight in force to roll and a person can only extert their weight in force, and that a single 10-year-old child weighs 75 lbs, we must limit the weight of the water hippo to 150 lbs which is ~13 gallons assuming 1/4 of the weight of the water hippo is structure.
  • Water Filling, Transport & Emptying
    • As these devices are meant to be used in rural areas, filling could either be done from a well or open body of water. It must therefore be able to be filled from either lying on its side or standing up on one end. The same applies for it being emptied. For transport, it must be mobile by either one child or woman over rough terrain (think a hiking trail).
  • Water Cleaning
    • A built-in water filter that would act during filling or emptying will help with improving water quality. Also, it is possible to add a water-purification chemical to the water before transport so that the resulting agitation during travel mixes and cleans the water.

Current Concept Configuration

  • Recycled Hippo - The EWB team has noted that there are many plastic barrels left about from the shipping of oil, kerosene, gasoline or vegetable oil. These barrels are often picked up by the locals, cleaned out and reused for various purposes. There are also many worn Range Rover tires left about. These can be used to tire the barrels and allow them to be more durable for rolling transport. For structural integrity, the tires need to be as close as possible to the bands of the barrel. To pull it, a belt will be looped around its center and run to a pulley and lubricated dowel. One or two people may pull it by the dowel depending on how heavy it is. For water purification, a small amount of bleach or charcoal can be added to the water before transport so that agitation ensures all the water is cleansed. The former will require the barrel to stand open overnight to allow the chlorine and remaining bleach to vaporize and possibly need boiling. The latter only needs boiling.

Old Concepts

  • Water Centipede - A series of 10 liter volume segments that are linked together like the segments of a centipede. Plastic caps could be molded to have corresponding mate points to achieve this. Also, the plastic caps could be used to cap rubber inner tube segments to form a container. Ports on the caps will allow for filling. As the centipede is segmented, it will be easier to carry and fill each segment to a body of water that is on low ground compared to the hippo. The end pieces of the centipede will be attached to a rope or yoke to allow the assembly to be rolled on the ground. As the caps and the inner tubes can be disassembled and compressed, shipping is eased.
  • Wooden Water Cart - Craft a water cart of wood for carrying wooden or clay water jars. May require beasts of burden to roll and will depend on available resources.
  • Woven Water Hippo - Make a roller that has a wooden container, but has been woven over for reinforcement and easy of rolling.

Interested People

  • Spacefelix - EWB Liaison, Maker
  • Omegix
  • Your Name Here