Patterns in water bacteria communities

Ameet has discovered patterns in bacterial communities. This is a first step to making predict and correct happen, he says. 

Here are the patterns he has found:

1. If a type of bacteria grows on the treatment plant filters, it usually shows up at the tap.
2. Changes in the bacterial community increase as they travel along the pipes.
3. As time passes the bacterial community in the pipes gets steadily different from the community at the treatment plant.
4. Communities look similar at the same time of year - there's a seasonal pattern.
5. How often a bacterium is found in samples is a good measure of its abundance in the whole system.