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FINAL REPORT -Spectrum Labs Inc.


Class 1 and Absolute Particulate Reduction

Other Doulton system tests

Report Number - 0561D-020794 - revision 1

to: Mr. Anthony Frost, Doulton Water Care
from: Spectrum Labs Inc., 301 West County Road E2, New Brighton, MN 55112

November 15, 1994

original signed by:
Sandra L. Games (15/11/94) and Margeret L. Bicking (22/11/94)

Doulton Water Care has developed a proprietary drinking water treatment system that utilizes a radial flow activated carbon block filter cartridge in conjunction with a ceramic candle to remove specific contaminants from drinking water. This product is designed for long life filtration and is available directly through Doulton Water Care to distributors and retailers of point of use (POU) home water filtration systems.

The use of activated carbon block filter cartridges incorporating proven sorbent technology is becoming more prevalent in the design and development of drinking water treatment devices as manufacturers seek to combine the contaminant reduction capabilities of both organics and heavy metal removal technology. Ceramic filter cartridges are commonly used for the removal of harmful bacteria and cysts. Each technology has been established as an effective means for specific contaminant reduction under defined operating conditions.

Reliable information on contaminant removal capabilities is important in marketing this product to potential distributors and to the general public. Furthermore, several states have now implemented regulations which govern the sale and marketing of residential water treatment systems. Therefore, it is now necessary to have verification of contaminant reduction claims by a state certified independent third-party laboratory, using an approved protocol. Spectrum Labs, Inc. is pleased to provide this laboratory report as the result of an independent evaluation of the Doulton HIF under counter drinking water treatment system containing an Ultracarb filter cartridge for Class I and absolute particulate reduction.

Experimental Section

Selection of Analytes and Spiking levels

The Doulton HIF under counter drinking water treatment system containing an Ultracarb filter cartridge was evaluated for Class I particulate reduction in accordance with NSF Standard Number 42, "Drinking Water Treatment Units/Aesthetic Effects." Appendix C, "Particulate Reduction Performance," revised June 1988. Influent challenge waters were prepared by adding a known amount of Powder Technologies, Inc. (PTI) fine test dust to achieve a target spike level of 10(4) particles/mL of 0.5- 1.0 micrometers. Also, a single pass retention efficiency test was performed to determine a 0.5 and 0.9 absolute micron rating.

Influent and effluent samples were analyzed for both Class I and absolute particulate reduction evaluations using American society for Testing and Materials (ASTM) Method Number 795 which is a standard particle counting method. The corresponding Method Detection Limit (MDL), EPA Maximum Contaminant Level (MCL). and Target Spike Level for this analyte is provided in Table I.

Table 1

Analyte Selection for Contaminant Reduction Studies

Analyte ASTM Method Method
Target Spike Level
F795 N/AN/A10(4) particles/ml 0.5-1.0 micron size
and 0.5 and 0.9 micron absolute
1: PTI Fine Test Dust was used as a surrogate.

Experimental Design

The experimental and mechanical system design for the Class I particulate reduction evaluation was based on the test protocol contained in NSF Standard Number 42 and the absolute particulate reduction evaluation was based on ASTM F795. Both designs allow for the uninterrupted testing of two identical units simultaneously.

All influent samples were taken immediately prior to the test units to demonstrate that the mechanical test system had no effect on the water characteristics or on the concentration of the challenge analyte. Pressure gauges and flow meters were installed appropriately to allow documentation of system operation.

Test units were installed, conditioned and operated according to the manufacturer's instructions. Prior to spiking the challenge water, background influent and effluent samples were collected until samples obtained a steady state condition. Samples for the Class I particulate reduction evaluation were collected at the start of the initial cycle, at the start of the fourth cycle and when the unit reaches 75 percent reduction in flow or when the pressure drop across the unit reaches 40 PSIG. Spiked challenge water was passed through each test unit using an operating cycle of 50 percent on, 50 percent off with a 3 minute cycle, 16 hours per day, followed by an 8 hour rest period under pressure. Samples were collected for each test at the beginning of the "on" cycle immediately following the passage of one unit volume. Samples of influent and effluent water from the absolute particulate reduction evaluation were collected within 30 seconds after starting the injection of challenge water.

Particulate Reduction Results

The results of laboratory analysis for the Class I particulate reduction evaluation are summarized in Table 2. Table 3 summarizes the results for the absolute particulate reduction evaluation. The influent and effluent results for each sample point are tabulated along with the percent reduction. Both units evaluated meet the current NSF acceptance levels of at least 85 percent particulate reduction for a Class I filter rating.

Results from Particulate Reduction Studies for the Doulton Under counter Drinking Water System with Ultracarb candle

Table 2 Test Unit 1 Test Unit 2
SamplesParticle Size Range
Flush0.5-1.05162 2873  3891 
First Cycle0.5-1.0 2356900 21863 99.07 14890 99.37
Fourth Cycle0.5-1.02459174 11344 99.54 18242 99.26
75% of Flow 0.5-1.0 4093947 14895 99.64 36640 99.10
Flush 1.0-5.0 2 0   1  
First Cycle 1.0-5.0 377272 384 99.90 667 99.82
Fourth Cycle 1.0-5.0 404628 366 99.91 745 99.82
75% of Flow 1.0-5.0 873981 7766 99.91 3565 99.59

Instrumentation: HIAC/Royco 8000A Counter, LD400 Sensor
Fluid: DI Water
Contaminant: PTI Fine Dust
Initial Flow Rate: Unit 1=0.47 gpm, Unit 2=0.58 gpm
Final Flow Rate: Unit 1=0.13 gpm, Unit 2=0.15 gpm
Gallons Treated: Unit 1=7.6, Unit 2=8.1

Results from Absolute Particulate Reduction Studies for the Doulton Under counter Drinking Water System with Ultracarb

Table 3 Test Unit 1 Test Unit 2
Particle Size
0.5-0.8 584528448 83910 99.9856 61137 99.9895
0.8-0.9 24063648 102 99.9996 120 99.9995
0.9-1.0 19505472 56 99.9997 73 99.9997
1.0-1.5 28473984 16 99.9998 22 99.9998
>2.0 15753024 14 99.9999 19 99.9999

Instrumentation: HIAC/Royco 4200 Counter, LAS 346 Sensor
Fluid: DI Water
Contaminant: PTI Fine Dust
Initial Flow Rate: Unit 1=0.5 gpm, Unit 2=0.43 gpm


The Doulton HIP undercounter drinking water treatment system containing an Ultracarb filter cartridge was found to be very effective at removing particles from spiked challenge water. Calculated particulate reduction percentages were 99.0 percent or greater in both test units. This substantially exceeds the current NSF International Standard Number 42, Appendix C acceptance level for a Class I particulate reduction claim of a minimum 85 percent removal of particles in the 0.5-1.0 micron size range.

Particulate Reduction for Doulton Ultracarb candle

Live cysts test at University of Arizona US | Live cysts test at Water Research Council (WRc) UK | E.coli test UK | NSF standard 53 turbidity US | NSF standard 53 lead US | Serratia marcescens and escherichia coli bacteria test UK | Salmonella typhi, shigella dysenteriae and vibrio cholerae Inaba bacteria test UK | NSF standard 42 chlorine US | Pesticides and herbicides test UK | E.coli, heavy metals and THM's test Hong Kong

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