The Saguaro Rain Collector is a stylish water conservation product that complements your garden while allowing you to conveniently pressurize and use your collected water. Conventional rain collectors rely on the user to repeatedly fill a watering pail or install an expensive electrical water pump. The Saguaro stores rain channelled by your downspout and is made of rotationally moulded polyethylene dyed to mimic terra cotta pottery. It employs an ordinary bicycle pump to store 550 Kpa of pressure in a 20 L air tank. A pressure regulator releases the stored pressure to keep the body of the rain collector at a constant 70 Kpa. The air tank takes less than 5 minutes to pressurize and holds enough air to discharge 100 L of water. It can withstand 1700 Kpa and is equipped with a pressure release valve to ensure safe operation. This practical and cost effective improvement makes the Saguaro Rain Collector an appealing water conservation option to a society striving for sustainability.
The concept of a pneumatically pressurized rain collector was chosen as the most commercially viable product from over 60 proposals for a practical case study involving a gardening company. I was motivated to look into their rain barrels after reading that only 3% of the Earth’s water is fresh water, of which over two thirds is locked up in glaciers and ice caps yet over 60% of domestic water consumption is for outdoor use. We water our plants and wash our cars with valuable, clean fresh water when we really don’t have to. I set out to capture the voice of the consumer by reading customer reviews and interviewing home owners at an Interior Design Show and a Green Living Show. I concluded that most home owners are interested in the idea of collecting rain but are put off by the unappealing look and impracticality of the current products on the market. I started brainstorming for ideas of a practical and cost effective means of collecting and using rain water in a stylish package.
To determine if the concept would be functional, a small prototype was constructed out of flexible tubing and a water bottle. The development process began by determining how the small scale prototype would scale to a 100 L barrel and still be cost effective and practical for the user. To ensure practicality the product would need to: maintain an even pressure throughout the watering session, be capable of quick pressurization with minimal effort and not exceed the price of current rain barrels on the market. These criteria led to the development a separate air tank storing precisely the amount of air required to expel 100 L of water at a constant pressure. A safe and achievable pressure of 550 Kpa was chosen to be stored. Thermodynamic calculations reveal that a 20 L air tank would be required if the water barrel is to be kept at 70 Kpa. Over a period of two weeks suitable components were acquired and a full scale prototype was constructed.