I recently concluded an experiment in which I followed the first method from this website -- https://www.wikihow.com/Measure-Surface-Tension . The value that I was getting is about 0.25 N/m approximately which is much higher than the actual one of .07 N/m . The water that I have been testing is Indian tap water so I assume that 1 reason why it varies so much is because of the impurities present in it. However, can anyone help me to correct the error that I am having or explain to me why the value that I am getting is actually fine?
Also, a similar experiment done by someone else https://prezi.com/1pop46g01pvr/measuring-the-surface-tension-of-water/ yielded more or less equally differing results.