A report released Tuesday found Flint, Michigan, residents paid the highest residential water rates in the United States last year, despite its highly corrosive source. The Food and Water Watch study examined the 500 largest water systems in the country and found, on average, Flint residents paid around $864 per year for water service, which is nearly double the national average. Lawyer Valdemar L. Washington has sued twice to reduce the rates, and last year a judge ordered the city to reduce the charges by 35 percent. The city charges residents for the water they use and a connection fee for the water system. Washington claims the ruling was supposed to apply to both, but has only reduced the water charge. His lawsuit is on hold while the Michigan Court of Appeals considers it. The study was calculated before the judge’s ruling in January 2015.