How do you test to see how much bacteria growth occurs in reused water bottles?

Question

How do you test to see how much bacteria growth occurs in reused water bottles?

Answer 1

you need a fair bit of equipment for this...here's how I'd set it up:

you need to have sterile saline....add about 100mls of it to the bottle and shake vigorously...then you take a small amount of this water (100 microlitres and spread it onto a sterile agar bacteria plate (using LB medium) and let it grow overnight...count the number of colonies on the plate and multiply by 1000...you need to also do the same thing to an unused water bottle and compare them.