To what level should sample bottles be filled?

Sample bottles should be filled just above the line or about one inch from the top for several reasons related to the integrity and accuracy of water quality testing. This filling level allows for proper air space at the top of the bottle, which is crucial for preventing contamination and ensuring that the water sample can be properly preserved.

When the bottle is filled to the top, there is a risk of overflow or spilling, which can lead to the loss of sample and possible contamination from the environment. Conversely, filling the bottle too low could result in insufficient sample volume for the necessary tests, potentially skewing analysis results.

Maintaining a consistent distance from the top also allows for ease of handling and reduces the risk of contamination when sealing the bottle. This is particularly important for samples that require specific preservation conditions, such as temperature control or minimizing exposure to air.

Thus, filling just above the line or about one inch from the top strikes the right balance, ensuring that the sample remains viable for accurate testing while also minimizing the chances for contamination or loss.