Table 3.

Sampling points as increasing volume was passed through filtration units (without biofilm formation)

Unit	50% Standing volume (V1)	120% Standing volume (V2)
Sleeve unit	13 L	30 L
Disk unit	17 L	41 L*

^*After 41 L had passed the filter, the remaining volume flowing from the system was not sufficient to collect 2 L samples from basin and effluent. A 400 mL sample was collected at the effluent for bacterial analyses. 1 L from the standing volume was taken for Cryptosporidium parvum analysis rather than 2 L.