How Does the Water Filter Work?

The technology behind the Water Filters is saving lives. Using this unique but simple filter, over 100 gallons of clean water can be produced daily (up to 240 gallons per day in good conditions). Besides the filter kit, the only “equipment” needed is a 5-gallon bucket.

  • • The design of the filter is simple
  • • The construction is fast.
  • • And the maintenance is low.

For a low one-time cost, people in more than 70 impoverished countries now have safe drinking water.


The Way It Works

Water filters use a technology initially developed for kidney dialysis. Hollow Fiber Membranes are made of small U-shaped micro tubes. Going through tiny micro pores, water enters the cores.


These pores, called Point ONE Filter’s, are just 0.1-micron absolute.


As a result, cholera, E. coli, and typhoid-causing bacteria, as well as protozoa, cannot pass. Of all the filtration systems currently available, this one offers the highest removal level at 99.99999% while maintaining a high flow rate based on the large number of tubes.


At 0.1 micron absolute, there is no way for bacteria or protozoa to pass through, and at 0.02-micron absolute, viruses, protozoa, and bacteria are blocked. With a simple design and easy construction, families in third-world countries do not have to mess with purification chemicals, digging wells, or constructing sand filters.


Instead, all they need is the filter kit, a 5-gallon bucket, and a water source to enjoy clean, safe water in minutes.


For setup, a 1.5-inch hole is drilled in the bottom of a clean plastic bucket. The connector, hose, and filter are then screwed onto the bucket. After being filled with water from virtually any source, the filter head is lowered below the water line allowing gravity to work.


Having such a high flow rate at 10 gallons per hour, there is no need to store water, which dramatically reduces the risk of contamination. Working on gravity alone, this water filter is an extremely cost-efficient solution. For just pennies a day, a single filter is enough to provide safe drinking water to a family, a school, or an entire village.


The Water Filter is also easy to maintain. If the filter becomes clogged or the flow rate slows, an included syringe filled with clean water is used to backwash the filter.


Although the water filter is used for daily living, it is also an excellent solution during a natural disaster. Regardless of the situation, the water filter prevents a number of waterborne diseases.


• Bacteria – At a success rate of 99.99999%, the bacteria that cause amoebic dysentery, botulism, cholera, coliform bacteria, E. Coli, salmonella, leptospirosis and streptococcus are eliminated


• Protozoa – Also at a removal rate of 99.99999%, protozoa, also known as cysts, are removed, which prevents diseases like cyclospora, cryptosporidium, and giardia.



Microbiological Testing of the WaterBringsLife Water Filters

Produced for Kung Charities

Prepared by :

Thomas Soerens1, Andrew Nevin2, Laura Ritenour2, Holly Ross2, Shaun Egolf2, Megan Bleacher2, Kiera Jeschke2, Daniel Lemen3, Alyssa Sargent2, Chelsea Toburen4 1Department of Engineering, 2Department of Biological Sciences, 3Department of Chemistry and Biochemistry, 4Department of Nursing

One College Ave Suite 3034

Mechanicsburg, PA 17055

USA

April 21st, 2016


Summary

The WaterBringsLife Water Filter was tested for its ability to remove three microorganisms – Escherichia coli, Serratia marcescens, and Micrococcus luteus – using USEPA approved procedures.


These organisms were added to test water to reach a 108 – 109 cells/L initial concentration. The test water conditions met the criteria for “test water #3” as set by USEPA 1987. Each of the three tested WaterBringsLife Water Filters surpassed the target reduction of 6 log units, or 99.9999%, for each test organism. The WaterBringsLife Water Filter meets the USEPA standards for bacteria and protozoans.


Table 1. Mean log removal values (LRV) for three replicate filter tests. Water was collected and microbiologically analyzed after 100, 300 and 600 milliliters passed through the filter; standard error for these three samples is displayed. Filter Tested


Organism 1 2 3


E. coli 8.46 (±0.00) 8.46 (±0.00) 8.46 (±0.00)

S. marcescens 8.88 (±0.00) 8.88 (±0.00) 8.88 (±0.00)

M. luteus 7.73 (±0.00) 7.73 (±0.00) 7.73 (±0.00)

Introduction

Filtration is “a pressure- or vacuum-driven separation process in which particulate matter larger than 1 μm is rejected by an engineered barrier primarily through a size exclusion mechanism and which has a measureable removal efficiency of a target organism that can be verified through the application of a direct integrity test” (40 CFR 141.2). The WaterBringsLife Water Filter underwent challenge testing with specific microorganisms to determine if it performed as an effective barrier to those organisms. Standard United States Environmental Protection Agency (USEPA) approved procedures were followed. Three WaterBringsLife Water Filters provided by Kung Charities were tested.


Each filter was conditioned with a 5% chlorine solution and sterile test water. The challenge microorganism (Table 2) was mixed with test water to obtain a 108 – 109 cells/L concentration and was forced through the filter. 100 ml of filtrate were collected in a sterile Whirl-Pak® Bag after 100, 300 and 600 milliliters passed through the filter and analyzed for microbial growth using the membrane filtration technique following Standard Methods 9222 (APHA et al.,2012).


Surrogate organisms of similar size, approved by the USEPA, were used in place of the pathogenic target organisms to avoid unnecessary safety hazards.


Table 2. Challenge test organisms and USEPA approved surrogates. (USEPA, 2005 and NSF, 2005)

Target Organism Surrogate Size range (μm)

Pathogenic Coliforms Escherichia coli 1-1.5

Cryptosporidium Serratia marcescens 0.5

Giardia Micrococcus luteus 7-12


The USEPA Guide Standard and Protocol for Testing Microbiological Water Purifiers (1987) requires a minimum reduction for protozoan parasites of 3 log units and a minimum of 6 log units for bacteria. For this test, all targeted log reductions for surrogates were set at 6 log units, or 99.9999% reduction. Surrogate organisms were chosen according to guidelines in the EPA Membrane Filtration Guidance Manual, published June 2003.


Methods

Test Water and Solutions

Test Water: The water used for testing was obtained from the Yellow Breeches Creek, which is the source for municipal drinking water in Cumberland and York Counties in Pennsylvania. Water was collected in a 20L carboy and autoclaved at 121°C (15 lb pressure) for 35 minutes to obtain sterile test water.


Standard methods (APHA et al., 2012) were followed to ensure test water conditions. Trypticase Soy Broth (TSB) (BD Diagnostic Systems) 30 g dehydrated TSB was dissolved into 1 L of reagent grade distilled water. The agar was then dispensed in culture tubes and 250 ml flasks, covered with caps/foil and autoclaved at 121°C (15 lb pressure) for 15 minutes. Trypticase Soy Agar (TSA) (BD Diagnostic Systems) 40 g dehydrated TSA was dissolved in a flask containing 1 L of reagent grade distilled water and heated to boiling with stirring until the ingredients dissolved. The agar was then autoclaved at 121°C (15 lb pressure) for 15 minutes. It was aseptically poured into 50x9 mm petri dishes to 4-5 mm depth (7 ml) and allowed to solidify. The plates were stored for up to two weeks in the refrigerator.


Bacterial Growth and Challenge Water Preparation

Stock cultures were quadrant streaked onto TSA plates and incubated at 30°C (M. luteus,S. marcescens) or 37°C (E. coli) for 24 hours.


A pure culture was selected from the plate and used to inoculate a culture tube containing 10 ml of TSB. The tube was incubated with spinning at the temperatures given above overnight to grow the cells to stationary phase.


The following day, the cultures with back – diluted into 10 ml of TSB at a concentration of 1:100. After approximately 2-4 hours of growth at 37°C on a shaker plate, the culture tubes were observed with a spectrophotometer in order to determine optical density (OD) and the phase of growth. When the cultures had achieved an OD of .55-.6 absorbance, to ensure the cells were still in exponential growth phase, the cultures were then diluted in 2.5 L test water to obtain a final concentration of 107 -108 cells/100 ml (108 -109 cells/L) after mixing. Test water was then distributed into 2 L vacuum bottles for challenge testing. Initial seed counts were confirmed by serial dilution using 99 ml sterile deionized distilled water blanks. The final dilutions for plated by membrane filtration (see below) were 10-5, 10-6, and 10-7.


Sample Collection

All tubing, bottles, caps, and glassware were washed and autoclaved prior to each trial. Initial conditioning of the water filter was attained by passing 200 ml of 5% bleach solution followed by 1 L of sterile test water (without organisms) through the filter (Fig. 1). Negative controls were collected from the final 100, 300 and 600 milliliters of test water in sterile Whirl-Pak® Bags. Challenge test water with organisms was forced through the filter. Collection of filtrate was performed at 100, 300, and 600 milliliters in sterile Whirl-Pak® Bags.


Microbiological Analysis

Standard Methods 9222 (APHA et al. 2012) were followed; the following description is abbreviated. The 100 ml sample was shaken vigorously and poured into the funnel. Vacuum was applied to filter the sample through. Vacuum was turned off and funnel top lifted. Using sterile forceps, the filter was transferred to the prepared petri dish by placing the filter grid right side up on the agar surface with a slight rolling motion. Plates were incubated at 30°C (M. luteus, S. marcescens) or 37°C (E. coli) for 24 hours, and the number of colonies was counted.


Calculations


Colony forming units (cfu)

Cfu/100 ml = 100 x (number of colonies) / volume of sample filtered in mL

Log removal value (LRV)

Target is 6 log unit reduction.

LRV= log (Cf) – log (Cp)

Cf = feed concentration (cfu/100 ml)

Cp = filtrate concentration (cfu/100 ml)


Results


All trials had outcomes of zero cfu/100 ml in each test organism and control filtrate (Table 3). All trials attained 6 log unit reduction or higher. (Table 4)

Table 3. Challenge filtration test trials for three water filters.

Filtrate collected at 100, 500, and 900 milliliters were plated using the membrane filtration technique. Values are expressed as colony forming units per 100 milliliters (cfu/100 ml).

Trial Organism Initial seed 100 300 600

1 E. coli 2.95 x 108 0 0 0

S. marcescens 7.61 x 108 0 0 0

2 M. luteus 5.47 x 107 0 0 0

Negative control 0 0 0

E. coli 2.95 x 108 0 0 0

S. marcescens 7.61 x 108 0 0 0

3 M. luteus 5.47 x 107 0 0 0

Negative control 0 0 0

E. coli 2.95 x 108 0 0 0

S. marcescens 7.61 x 108 0 0 0

M. luteus 5.47 x 107 0 0 0

Negative control 0 0 0

Table 4. Log removal values (LRV) for each trial. The target reduction was 6 log units or greater.

Trial Organism 100 300 600

1 E. coli 8.46 8.46 8.46

S. marcescens 8.88 8.88 8.88

M. luteus 7.73 7.73 7.73

2 E. coli 8.46 8.46 8.46

S. marcescens 8.88 8.88 8.88

M. luteus 7.73 7.73 7.73

3 E. coli 8.46 8.46 8.46

S. marcescens 8.88 8.88 8.88

M. luteus 7.73 7.73 7.73


Discussion


All three WaterBringsLife Water Filters showed a 6 fold or greater reduction of all test organisms, indicating that the WaterBringsLife Water Filters successfully remove the organisms from the challenge water. The surrogate organism used for Cryptosporidia and Giardia, Serratia marcesens, achieved greater than a 6-log reduction in effluent. The EPA only mandates a 3-log reduction for these organisms so the WaterBringsLife Water Filterstested far exceeded the EPA minimum standards. Because 6 log reduction of all organisms was observed, these tests show that the WaterBringsLife Water Filter meets the USEPA standard for both bacteria and protozoan removal.


References


American Public Health Association (APHA), American Water Works Association (AWWA), and Water Environment Federation (WEF) 2012. Standard Methods for the Examination of Water and Wastewater. 22nd ed. American Water Works Association.


Federal Register 2012. National Primary Drinking Water Standards. 40 CFR 141.2 NSF International. 2005. EPA/NSF ETV Equipment Verification Testing Plan for the Removal of Microbiological and Particulate Contaminants by Membrane filtration. Ann Arbor, MI.


USEPA 1987. Guidance Manual for Compliance with the Filtration and Disinfection Requirements for Public Water Systems Using Surface Water Sources Appendix O: Guide Standards and Protocol for Testing Microbiological Water Purifiers.


Contract No. 68-01-6989 U. S. Environmental Protection Agency, Office of Water and Office of Research and Development, Washington, DC. USEPA 2005. Membrane Filtration Guidance Manual. EPA 815-R-06-009 U.S. Environmental Protection Agency, Office of Water and Office of Research and Development, Washington, DC.


Our Service

Our goal is to provide water filters to young kids across the globe for FREE. The water filters last many years: 500-thousand gallons. That’s almost 12 years using the filter every day- 8 gallons an hour.