Bailers offer an affordable and efficient grab sample, and they are available in a variety of lengths, diameters, and materials. They are widely used for shallow sampling and for sampling groundwater from monitoring wells in all phases of groundwater investigations. Stainless steel models may be decontaminated between uses; single-use, disposable models are also available.
Sampling is accomplished by attaching the bailer to a line and lowering it to the desired sampling depth. As the bailer is lowered, the bottom check valve allows liquid to flow through it. When it is retrieved, the weight of the liquid closes the bottom check valve – preventing the liquid from escaping through the bottom of the bailer. The sample is a composite of the liquid present at the depths between the top and bottom of the bailer when the check valve was closed.
Bailers are easy to use, relatively inexpensive – compared to hand pumping methods – and do not require a power source. They may be used to sample most depths, although deep sampling may be time-consuming.
