In 2001, legislative measures were introduced in the UK to restrict usage of antifouling agents in small (<25 m) vessel paints to dichlofluanid, zinc pyrithione and zineb. This removed the previously popular booster biocides diuron and Irgarol 1051 from the market. To investigate the impact of this legislation, water samples were taken from locations where previous biocide levels were well documented. Results from analyses demonstrate a clear reduction in water concentrations of Irgarol 1051 (between 10% and 55% of that found during pre-restriction studies), indicating that legislation appears to have been effective. Although other booster biocides were screened for (chlorothalonil, dichlofluanid and Sea-Nine 211), they were below the limits of detection (<1 ng/l) in all samples. A survey of chandlers and discussions with legislative authorities supports these results and concurs the removal of Irgarol 1051 based paints from the market using simple regulations at a manufacturer level with little regulation at a retailer level.