Lack of safe water and proper sanitation is a very real crisis worldwide crisis. Unsafe water steals the lives of 5,500 people each day. Yet, the tragedy of unclean water often fails to make the headlines. It is a silent killer — one that quietly preys on the world’s most marginalised and forgotten people.

The Project: Building an efficient and easier-to-use water filtration system
Water Missions International (WMI) is a Christian, nonprofit organisation dedicated to providing clean, safe water to people in developing countries and disaster areas through a variety of technologies. Its mission is to provide sustainable access to safe water so that no person will perish for want of clean drinking water.

Water Missions International has been able to develop low-maintenance, self-sustaining water treatment systems for communities around the world that provide safe drinking water, wastewater management and storm water control. Its system design works well, but it is labour-intensive to produce and must be disassembled for shipping, then reassembled in the field. For this reason, WMI has committed to a process of redesign and improvement. The two-fold goal: to reduce the overall system footprint so more units can be shipped in the same space, plus incorporate as many moulded plastic parts as possible to reduce cost and improve production rates.

The Challenge: Building a working prototype to test the new design before committing to production
Redesign of WMI's water filtration systems involved creating nearly 40 different working components. Because a project of this size and complexity would require an investment at least $300,000 in tooling alone — a huge cost for a non-profit organisation — it was determined that a fully functional prototype system must first be designed, built and evaluated before actual system would be produced.

For high quality prototypes of this type, the stereolithography (SL) process would be used to develop individual components because of its well-established capability to produce parts with tight tolerances.

The Solution: DSM Somos WaterShed XC 11122
For this application, Somos stereolithography resins were selected as the materials of choice because of their ability to handle exposure to running water and high pressures without failing. WaterShed is an optically clear rapid SL prototyping resin developed by Somos to provide ABS-like properties, clarity and excellent temperature resistance. In this application, it produced clear, functional, accurate parts simulating acrylic in appearance.

Most importantly, WaterShed XC 11122 provided the lowest available water absorption versus alternative SL resins. The resistance of this resin to moisture resulted in excellent dimensional and physical property stability and facilitated direct rapid manufacturing of the entire water filtration system using the stereolithography process.

The Result: A fully functional, easy-to-install-and-use water filtration system
The new water filtration system design, prototyped using WaterShed XC 11122 was rigorously evaluated using a variety of tests. This included running the system at maximum capacity, identically to what it would experience in the field. The pump was run at 90 PSI, with flow rates of up to 15 gallons per minute. Additionally, the backwash components were cycled 7,500 times to simulate 20 years of operation with no failures or detectable wear. The prototype system handled the task successfully in all aspects. Since then, the system has also been tested numerous times and continues to perform as required.

The redesign also allows the units to be fully assembled and tested at the plant. It is now completely contained within the structural framework, reducing the possibility of damage during transportation. Because these water systems are sent to very remote areas of the world, manpower with technical and mechanical skills is not always readily available. Consequently, it is often necessary to absorb the expenses of hiring and transporting skilled installers from outside the area. The new system will significantly minimise the complexity of onsite assembly, resulting in a corresponding reduction of installation costs.

The Bottom Line
Using the new water filtration system prototyped with WaterShed XC 11122, WMI was able to reduce costs by more than $700 per unit. The previous system, using stainless steel brackets and individually machined nylon and PVC components, costs $750. It will now be replaced by injection moulded polycarbonate and ABS components, costing just $45.

From a materials standpoint, testing proved that WaterShed XC is very capable of handling demanding physical stresses, as well as extensive exposure to water. Water Missions International was therefore able to move from the prototype phase into production with assurances that money spent would result in everything working as required.

For more information on WMI, call: +1 843 769 7395, or visit: http://www.watermissions.org/

Bruce Okkema, President, Eagle Design and Technology, Inc.