Or, you can place several samplers at each site and retrieve them after different intervals. Sample bacteria as often as you can while the samplers are in the water. Samples for bacteria testing should be collected when samplers are placed and retrieved. If possible, also collect samples at least once while samplers are in the water. Sample during dry and wet weather.
Wet weather has potentially contradictory effects.
On the one hand, it may cause septic systems to fail. On the other, it dilutes the OBs. Wet weather also washes natural, fluorescing dissolved organic compounds into the water. So, sample during dry and wet weather to get the whole story. Train monitors to recognize fluorescence.