'Coffee-Ring Effect' Harnessed to Provide Rapid, Low-Cost Analysis of Tap Water (image) American Chemical Society Share Print E-Mail Caption Tap water droplets from two buildings on the Michigan State University campus leave behind different coffee-ring patterns; "hard" water is shown on the left, and water treated with a softener is shown on the right. Credit Xiaoyan Li Usage Restrictions Please credit Xiaoyan Li when using this image. Share Print E-Mail Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.