Please call Rock River Laboratory, Inc. at 920-261-0446 for proper bottles, and postage paid mailers. Certain tests (especially Hardness, Sulfate, and Nitrate-Nitrogen) require the use of specially prepared bottles. Samples should consist of at least 250ml (approximately 1 1/2 cups) of water. After collection, it is best to refrigerate your samples. Ensure that they are kept cool and delivered to Rock River Laboratory, Inc. within 48 hours for best results. This process will ensure that we have a sample representative of your water supply.