Accounting information is widely used in benchmarking projects and for other comparative purposes. However, if comparability is low, the information from such comparisons can give incorrect information which in turn can lead to erroneous conclusions and decision making. In the past the level of harmonization of accounting practices as well as their comparability has been very low in the Swedish water and sewage sector. One explanation for this might be that most of the water and sewage operations were run by municipal administration and that until 1998 municipal accounting was only regulated on a voluntary basis. Through comparisons of survey data from the year before and five years after the 1997 legislation, this study analyzes whether the legislation has affected the level of harmonization. Even though municipal accounting now is regulated by law, the requirements for aspects such as auditing are still much lower for municipals than for companies; the requirements for accountability are much lower for municipal agents than for companies. The study also analyzes whether there is any relationship between form of association and level of harmonization. The results did not indicate any effect of legislation on harmonization. Surprisingly, the results did not show any significant relationship between form of association and level of harmonization.