Frequently asked questions about water quality For more information, visit this year's full water quality test results. What is UDF and why is it conducted? What if my water is discolored? Do I need to do anything? Will UDF increase my water bill? Why is UDF required? Does UDF waste a lot of water? When will the Flushing be performed? How will I know when and if my area is being flushed? How long will UDF take? Are there pharmaceuticals in my water? A company contacted me and said that I needed to purify my water. Do I? I got a notice in the mail that my water should be tested and that a company was conducting free inspections. Do I need to do this? Is this company with the city? What should I do if a company contacts me about water testing? Why does my water look rusty? Why does my water look cloudy? Why does my water smell like rotten eggs? What is GRU’s water hardness? What is the EWG study?