Headspace is the amount of air that remains inside the sample container after sample collection. For most analysis, some headspace will not cause a problem. Zero headspace is where there is no air bubble in the sample after it is capped. The easiest way to achieve this is to fill the sample container as full as possible, leaving some water above the container opening, then carefully putting the lid back on and tightening it down. If possible, you may alternatively close the sample container submerged in the sample. For some analysis, we provide special containers with convex lids to help facilitate this.

Zero headspace is preferred to give you the most accurate data that we can for tests including; residual chlorine (total or free), hydrogen sulfide, VOC and dissolved oxygen.