| LifeStraw® Family has been tested at the University of Arizona for longevity and microbial reduction performance. |
| |
| Results on Longevity |
| The longevity of the LifeStraw® Family filter has been assessed for a capacity of 18,000L. |
|
| After this volume of water containing turbidity and organic carbon was passed through the filters, the flow rate was still around 100 to 130 mL/min which represents 6 to 8 L/h. The flow rate values fluctuated between 200 – 320 mL/min at the beginning of the longevity trial, i.e. 12-19 L/h, and 6-8 L/h at the 18,000 L capacity. |
|
| The cleaning frequency was assessed as mentioned below: |
|
 Prefilter cleaning frequency: approximately every 30 hrs
(represents a less than daily cleaning in the real conditions of use) |
|
Filter cartridge cleaning frequency: approximately every 11 hrs
(represents a less than daily cleaning in the real conditions of use) |
|
Bucket cleaning frequency: approximately once a week.
(shows that the bucket requires less maintenance) |
|
| This longevity trial on the LifeStraw® Family filter demonstrates that the filter capacity lies around 18,000L or more. |
| However, in our user instructions, we are still recommending daily cleaning of the pre-filter and the purification cartridge. |
|
| Microbiological Efficacy |
| On average the following Log10 reductions for each microbe and for all three units during the lifetime of the filters was as follows: |
| Micro-organism |
LOG10 reductions
|
EPA requirements
|
| E. Coli |
6.8 |
6.0 |
| MS2 virus |
4.4 |
4.0 |
| Cryptosporidium oocysts |
3.6 |
3.0 |
| |
Conclusion:
The efficacy of the LifeStraw® Family filter has been assessed for the above microorganisms up to a capacity of 18,000L. This filter unit meets the EPA requirements of LOG10 6/4/3 reductions for these groups of microbes.
The micro-organisms used during the efficacy trial are representative of the ones encountered on the field. They have been chosen because they are particularly resistant to disinfection or particularly small in size, thus rendering their elimination difficult. |
| |
| The ageing water characteristics are mentioned below: |
| Water characteristics |
EPA standard of
ageing water
|
Ageing water used by
University of Arizona*
|
| Water pH |
6.5-8.5Roof |
7.5 + 0.25 |
| Total dissolved solids |
50-500 mg/litre |
50-500 mg/litre |
| Turbidity |
0.1-5 NTU |
15 NTU |
| TOC |
0.1-5 mg/litre |
5 mg/litre (as tannic or humic acid) |
| Disinfectant residue |
not detectable |
< 0.1mg/litre in active chlorine |
| Bacteria/virus/cysts |
not detectable |
CFU or PFU/100 ml or unit/L |
| |
| * Higher concentration of turbidity and TOC in the ageing and challenge water is being passed through LifeStraw® Family. This makes the water quality closer to field conditions. |
| |
| The challenge water characteristics are mentioned below: |
| Water characteristics |
EPA standard of
challenge water
|
Challenge water used by
University of Arizona*
|
| Water pH |
9.0 + 0.2 |
9.0 + 0.2 |
| Total dissolved solids |
1500-150 mg/L |
1500-150 mg/L |
Turbidity
|
> 30 NTU |
> 100 NTU |
| TOC |
10 mg/L |
> 10 mg/L (as tannic or humic acid) |
| Disinfectant residue |
not detectable |
at least < 0.1mg/L in active chlorine |
| Bacteria |
107-8 CFU/100 mL |
107-8 CFU/100 mL |
| Virus |
> 5 X 106 PFU/100 mL |
> 5 X 106 PFU/100mL |
| Cysts |
> 5 X 104 oocysts/L |
> 5 X 104oocysts/L |
| |
| * Higher concentration of turbidity and TOC in the ageing and challenge water is being passed through LifeStraw® Family. This makes the water quality closer to field conditions. |
| Complete test results for 18,000 litres are available on request. |
