Water Sampling: Recommended Guidelines
Sample Collection
Samples must be representative. Samples should be collected in clean, plastic bottles that have been rinsed three times prior to use. Well-water samples should be collected after pumping for at least 30 minutes. Sampling from distribution systems should be done after the lines have been flushed sufficiently to ensure that the sample is representative of the supply.
Storage and Transport
If NO3--N, NH4+-N or PO4--P are elements of interest the samples should be frozen or kept below 40° F. Samples collected for alkalinity, conductivity, phosphate, sulfate, turbidity or solids should also be refrigerated until analysis can be completed. Due to the problems of absorption or precipitation, if micronutrients, metals or salts are of interest, the sample, or a sub-sample, should be acidified.
Please take the following precautions when sending frozen water samples:
- Always leave at least 10% of the container unfilled to accommodate the expansion of the water when frozen.
- Do not place sample containers directly onto dry ice.
- Place some insulation between the dry ice and the sample containers.
- Do not use glass bottles.
Click here to view a summary of EPA recommendations for sample preservation and holding times: Sampling—EPA Requirements
References
Refer to references on this page.