The Biological Activity Reaction Test (BART™) is a water testing system for nuisance bacteria and can involve several different tests. These tests detect the activity of these nuisance bacteria by the time lag. The unique nature of the BART test which makes it very different, and possibly superior, to the agar techniques is that the water used in the test all comes from the sample and contains the microbes still within their natural environment. The water in the agar methods comes with the agar but it is tightly bound. This means that the microbes have to be taken from the water, placed into contact with the agar surfaces, and expected to "mine" the bound water for growth from the agar. Many microbes in the environment are not able to do this easily and so may be missed using agar cultural techniques. The BART uses a unique system for encouraging the microbes to grow in the test.