P19464: Water Purification System

Systems Design

Table of Contents

Systems Level Design Documents directory.

Team Vision for System-Level Design Phase

In this phase of our project our team planned to generate a concrete outline of each of the basic functions our planned unit would need to perform. A decomposition tree outlining these would be then used to create a comprehensive table of potential solutions for each necessary function. The culmination of the best of these ideas would be used to create a handful of preferred high-level systems to take into the prototyping and physical design phase of the project.

Our team achieved all of the expected goals for the phase. Located below we have included our functional decomposition with all lower level functions outlined, along with the morphological table that was generated to address these functions. 4 system level ideas were constructed and detailed for further analysis. Additionally our team was able to begin acquiring resources that could be used for testing and prototyping of our selected systems.

Functional Decomposition

From our Customer and Engineering requirements, the overall process as discussed in the Problem Definition was dissected as seen below.

"Functional Decomposition Diagram"

Concepts Generated from Function

Including many more that are in our Morphological Chart.


Four major device functions useful for benchmarking were identified using the results of functional decomposition:

Water Treatment Gold Standard Criteria

Benchmarking criteria were developed around the functional decomposition results and customer requirements. Our customer specified that biological decontamination of source water was more important than particulate filtration. The best solutions to this requirement that we identified for benchmarking are outlined below:

1. The gold standard for biological cleansing of water is boiling

2. The second best known method is on-market sub-micron pore size water filters

3. Boreholes are an alternative solution and water source

Quantitative Benchmarking Criteria:

Biomimetic Benchmarking:

Biomimetic approaches have been considered throughout concept development, and were also outlined as potential concepts and as potential benchmarks:

1. Certain trees are able to live in saltwater

2. Plants play a role in natural water table filtration

3. Some animals live in or drink salt water

4. Certain metals kill bacteria on contact

Morphological Chart and Concept Selection

Below is a representation of our master morphological chart which collects many of our ideas for solving the various steps in the functional decomposition. Below the larger chart are 4 examples of different ideas we had for complete systems. Our end resulting ideas were combinations of these pieces of the morph chart.

"Visual Morphological Chart"

"Example Selection 1"

"Example Selection 2"

"Example Selection 3"

"Example Selection 4"

Concept Development

Using the ideas collected in the morphological chart and applying the selected criteria within the Pugh analysis, our team selected 4 potential system-level solutions that we felt had promise. Described below is information on how each system would achieve all of the low-level components of the functional decomposition.

“The Catfish”

The Catfish is a static in-water filtering system that would passively collect water from within the river itself. Unlike our other 3 system level solutions, this system would filter dirty water whilst still in the river. One of the biggest appeals of this system is its simplicity and its ease of use. The system would contain no moving parts and therefore can be easily and quickly created for prototyping. The sketch below outlines the expected use and rough design of the Catfish system. Comparing this design to benchmarked criteria we found that the design excelled in durability and portability, whilst lacking in overall cost and the total quantity of clean water when being compared to the datum system.

"The Catfish"

“Water Hammer”

A water hammer, also known as a hydraulic ram, is a concept in which a large amount of slower moving water is used to powerfully pump a much smaller quantity of water. This concept is what causes the loud knock upon quickly turning a faucet on and off in your home. The system would be very durable and could be made with inexpensive, high strength plastic plumbing components that are widely available. Filtering for the design would occur on-shore using a purchased filter system for simplicity and guaranteed water cleanliness. The unit would be entirely passive and would require no human intervention beyond the initial placement of the device within the water source. Benefits of this solution include its high quantity of produced water and robustness using inexpensive materials, but overall design time and lack of unit portability would provide hurdles to overcome. Drawings below demonstrate how a water hammer would be expected to function upon placement.

"The Water Hammer"

“Spiral Pump” Designs

This design consists of two separate units that operate on the same physical principles. By adding a quantity of water to a spiral tubing system and rotating, pressure can be increased to move the water outside of the water source. Historically, this principle was used by an Archimedes Screw to lift water the height of the unit, but no higher. By altering the design of the screw unit, the pressure generated can become greater and therefore lift the water above the height of the unit itself, increasing usability. In the first design, a spiral of decreasing radii will be powered via the running river water or an external power source. The unit will scoop water into its largest radius and eject water from an exit hose to shore, where filtering using an on-market filter will take place. The main drawback of this system is portability, as its quite large to generate appreciable head. Units demonstrated a 6-foot diameter unit producing 40 feet of usable water head, our unit would need significantly less and therefore the size could be scaled down.

"The Spiral Pump"

The second design would be a modification of a current design known as a “Rife River Pump”. The general principle of the system is the same as the previous, a spiral uses increasing turns of water to maximize head. This design, however, encompasses a floating body, allowing the unit to be anchored at any point within the stream and harness its energy through a series of compact internal spirals. This version of the spiral pump can likewise generate significant head but comes with the benefit of being lighter and with a tighter diameter than the first described system.

"The Corkscrew"

Concept Selection

Pugh Analysis

Pugh Chart: Preliminary Screening/Overall

Pugh Chart: Preliminary Screening/Overall

Pugh Chart: Assessing Water Access Concepts

Pugh Chart: Assessing Water Access Concepts

Find our working pugh analysis chart here


Feasibility: Prototyping, Analysis, Simulation

To consider feasibility of our selections, we determined that our systems should be financially acceptable, able to produce our water requirement of 12 gallons a day, produce clean water with confidence that water borne bacteria and viruses have been removed, and meets our weight requirements for maneuverability.

All of these systems will use an off the shelf water filter as it would take years of research and an enormous amount of money to produce a better filter than what could be bought.

We also have ruled out using electricity as it involves expensive components which also tend to be fragile.

Financial Feasibility


Filter - $100 - $500

Funnel - $5

Sealed Bag - $15

Small Diameter Hose - $15 - $30

Hand Pump - $30

Anchor - $15

Total - $195+

The Catfish will need to go through controlled testing to get an estimate of gallons per day of water it can produce.

Water Hammer / Hydraulic Ram:

Water Hammer Pump - $200 - $300

Filter - $100 - $500

Small Diameter Hose - $15- $30

Total - $315+

The Water Hammer has working prototypes producing 30 gallons a day at heads over 50ft. This is more than enough to meet our requirements.

The Spiral Pump:

Filter - $100 - $500

Hose / flexible tubing - $20 - $50

Frame - $50

Hardware - $50

Small Diameter Hose - $15 - $30

Total- $235+

With a source flow rate of 3 ft/s and the spiral having a diameter of 6ft this system can produce 3900 gallons a day at a head of 40ft. We will attempt to downsize this system as those numbers are multitude above our requirements.

The Corkscrew Pump:

Filter - $100 - $500

Hose / flexible tubing - $20 - $50

Frame - $50

Hardware - $25

Small Diameter Hose - $15 - $30

Fins - $30

Total - $225+

Prototypes of these pumps have been able to produce 500 gallons of water a day at a head of 26ft with a source flowing at 1.5 ft/s

Conclusion: All of these systems are feasible in terms of pricing and 3 out of 4 are expected to be feasible in terms of functionality with one undetermined until testing. All of these systems also can be designed to fit inside a backpack.

Further Feasibility Analysis

Moving forward, the team will be preforming small-scale benchmarking in the Genesee River to determine outputs relative to size and design from our 4 selected concepts.

Systems Architecture

High level systems architecture. Taking the inputs and outputs and transforming them through the functions described in the functional decomposition.
Systems Architecture chart

Systems Architecture chart

Plans for next phase

For the next phase our team is planning on beginning some additional detailed analysis for our selected systems. This analysis will be used to guide preliminary prototyping as outlined in our benchmarking section.

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