Introduction: Water Wheel From Plastic Bottles

About: Openproducts' focus is on design of new products and on innovative approaches towards improving existing products. An example: the CountClock, a concept facilitating children to learn telling the time. Purpose…

This outdoor parent-child project is big fun and has educational aspects: a water wheel from reused bottles and branches is turning in a river's current and is towing a small boat in.

Main requirement is a small, fast-running and shallow (mountain) river. You'll also need some empty plastic bottles (including their caps), a number of bolts and nuts, rope and some branches.

Child's Age, Duration and Learning Aspects
This project is suited for children from approximately 5 years old onwards. Building the water wheel will take two to eight hours, depending on the level of preparation, the number of helping hands and their experience.

The educational aspects involved regard constructional principles (techniques like lashing and screwing, elements like axis bearing, blade, spool) and physical concepts (rotation, power, torque, kinetic energy). The water wheel is not intended for long-time use: it is rather a 'Design-for-a-Day' or demonstration model.

A parent is not only needed for a helping hand but also for safety reasons, especially when the child cannot swim. Don't access rivers that are under influence of hydropower facilities and may see sudden fall increases.

Instructables Contests
This water wheel has been submitted to three Instructables' contests:

Some words to motivate its entry to the latter contest: this water wheel gets one pretty much in touch with pre-civilization roots. Not only for its branches, stones and rope lashing, but also for its possible alternative applications. Instead of tugging a boat, the energy from the wheel might be used to start a fire by rubbing the axis into another piece of wood: feel free to demonstrate an automatic hydropowered lighter, perhaps even the first-ever. Moreover: hunters-gatherers had much more spare time (and on average lived longer) than their descendants the farming groups, possibly even more than the average 21st century man. So this project might have landed well at the time.

In this Instructable Step 1 below highlights some of the design features of this water wheel and Step 2 gives some directions on how to make it. Step 3 spends some words on dismantling the installation and Step 4 explains the CC BY license of this Instructable.

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Step 1: Design Features

The idea of installing a water wheel as a parent-child project in a river current is not new. Among others, it is documented in a book (in Dutch) entitled 'Water... een boek om uit te putten' (by Jan Scheper and Annelies Slüper-Hendrickx, ISBN 90 6238 898 1). This openproducts' project however has four features that differ from the concept described and that are worth mentioning:

  1. The blades have been made from empty plastic bottles;
  2. The bottles have been connected through their caps to yield a blade pair;
  3. An underwater frame has been made to better resist the river current; and
  4. A spool is used to do work.

Some elements introduced here might be applicable to a small bottle-based wind turbine, especially the way the bottles have been merged through the caps (point 2 in the list of features above).

The next step shows more detail on the construction.

Step 2: Making the Water Wheel

Empty plastic bottles were used to form the blades of the water wheel. Cut out part of the bottle side to obtain a blade form. By screwing the caps together as indicated in the pictures a pair of blades is resulting, perfectly suited to be lashed on a wooden axis. As can be seen from the video at the start of this Instructable four blades is not really enough: the water wheel equipped with eight blades runs much more smoothly.

Some remarks on the axis:

  • As the blades' center point is a little off the center of the axis it might be good to use a slightly curved branch to have the water wheel better centered;
  • Make sure to leave enough space on the axis for the spool;
  • In order to prevent the axis to fall out of the bearing it is suggested to have the axis hold out from the bearings (more than in the last picture above).

The force of the water stream is so strong that the support structure needs to be quite solid. This was reached by a stand-alone support based on some branches, lashed together with rope. Two Y-shaped branches were used for the axis bearing. The support structure was anchored by putting on heavy stones underwater to prevent it from washing away. An attempt to stick the Y-shaped beams into the river bed failed because stones and bedrock prevented it.

The rope for towing in small ships is simply wound around the axis. Unwinding is easiest by taking the wheel off its bearings.

The next step dedicates some words on dismantling the installation.

Step 3: Design-for-a-Day

This water wheel is not intended for long-time use: it is rather a 'Design-for-a-Day' or playing & demonstration model.

In order to prevent it from ending up in the plastic soup have it disposed or reused properly at the end of the day. The picture above has been released into the public domain by Fangz at Wikipedia.

The next step elaborates on the CC BY license under which this Instructable has been released.

Step 4: License

This Instructable is being made available through a Creative Commons Attribution (CC BY) license. Some design features of the concept have been described in Step 1.

Republishing this Instructable is allowed provided that it is properly attributed (cite the name openproducts, link to,, or the original Instructable). For other arrangements send a Private Message through the instructables member page (

Teach It! Contest Sponsored by Dremel

Participated in the
Teach It! Contest Sponsored by Dremel

Hand Tools Only Contest

Participated in the
Hand Tools Only Contest

Hunter-Gatherer Contest

Participated in the
Hunter-Gatherer Contest