Laboratory tests are normally used for phosphorus and nitrogen. Streamwatch kits have a field test for phosphorus and nitrogen. Suspended sediment is often measured in the field with secci discs, or perspex tubes. It can also be measured with a range of other devices. Faecal coliforms Faecal coliforms are bacteria found in the intestinal tracts of humans and most other mammals.
Testing is done by taking a water sample, and culturing colonies on agar plates in a laboratory.
It is not always an effective way of assessing health risk because faecal coliforms have different survival times in water to other bacteria, viruses, and parasites. Also outbreaks of various diseases in the population can lead to an increase in the level of pathogens in water bodies, without a corresponding increase in faecal coliforms. Organic materials in water create a biological oxygen demand when they are broken down by micro organisms. This can reduce disolved oxygen levels in water. Heavy metals and chemical contaminants are normally bound to sediment particles.