At what angle should the bottle be held while filling it for a sample?

Holding the bottle at a 45-degree angle while filling it for a sample is optimal for several reasons. This angle allows for a controlled flow of the water into the bottle, reducing the likelihood of splashing or introducing air bubbles, which can contaminate the sample or affect the accuracy of the results. It also enables the liquid to fill from the bottom upward, minimizing the risk of surface contaminants from the top layer of water in the sample source.

In comparison, a 30-degree angle may not provide a steady flow or might lead to difficulties in ensuring that all contaminants are avoided. A 60-degree angle may increase the chance of splashing, while a 90-degree angle could cause the water to pour too rapidly, increasing the risk of introducing air into the sample. Therefore, a 45-degree angle strikes a balance, promoting both a proper fill and the integrity of the water sample.