Table 2.

Biosand filter statistics and source water quality data collected in the Artibonite Valley, near Deschapelles Haiti, collected in March 2011*

Characteristic	Value
Flow rate (liters/hour)
Range	3–64
Average	25.1
Escherichia coli levels
Hand-dug well/open spring	87†
Piped spring/deep well	7
% Filtered water 0–10 MPN/100 mL	86
% Stored filtered water % > 10 MPN/100 mL	0
Overall bacterial removal efficiency	1.1 log10 or (92%)‡
Turbidity (NTU)
Average source water	4.7
Average filtered water	0.9
% Reduction	82
Regularity of post-chlorination	41%

^*E. coli levels of source water are calculated as geometric means. MPN = most probable number of coliforms; NTU = nephelometric tubisity units.

^†Includes one well with 2,419 MPN/100 mL that was too numerous to count or > 2,419.

^‡Excludes 11 filters that had no detectable E. coli in source water or filtered water.