For water quality monitoring, sampling time interval is set on a different day and time, so it can be differences in the quality of water every day and every hour. For example, if the first sampling is done on Monday at 06.00, then the sampling is then performed on Tuesday at 07.00, etc.
Frequency of sampling
The frequency of sampling for the purposes of monitoring carried out by the purposes or if it has not been established, then as a guidance to do the following:
- For streams / channels are heavily polluted, every two weeks, for one year;
- For river / canal is polluted mild to moderate, once a month, for one year;
- For natural water has not been contaminated, every three months for one year;
- For water lakes / reservoirs, every 2 months for one year;
- For groundwater flow, every three months for one year.
In the sampling, you should use a new container. If forced to use second-hand container, the container is treated with a particular treatment in advance, to ensure that the container is free from the influence of the previous sample. In addition, container or equipment which can react with the liquid waste must be avoided, for example, containers or equipment made of metal that can be corroded by acidic water.
The tools used must also be easily washed or cleaned to avoid contamination, easily and safely taken to the sampling location. Water sampling can be performed through the working steps as follows:
- Setting up a tool that has been calibrated for sampling in accordance with the state of water resources
- The tools are rinsed three times with the water sample to be taken
- Samples were taken as necessary; samples obtained were mixed evenly in the container while or containers must be free of contaminants
- If the sampling is done at some point, the volume of samples from each point must be the same.
- Determination of sampling points or sampling locations can be supported with GPS and camera