Water Company Clean Water and Sewerage Boundary Data (GIS)


I am a local government work trying to cut down the amount of council officer time spent on (amongst other things) querying various water companies about which properties they do and do not serve with 1) water supply and 2) sewerage.  Our area of responsibility is Gloucestershire so I wanted to produce two GIS layers of the county that deliniate the water and sewerage areas of responsibility for the varous companies. 

So far we have had a response from one company (GIS shapefile) but the other water companies seem to have maps of varying detail on their website, and many of them (and the information provided by "check your postcode" services on the water company websites) seem to be just incorrect in some cases, and misleading in others, particularly near to the boundaries of the various companies' areas.  Would it be too much trouble for someone in govermnent to produce an accurate and DEFINITIVE map of the boundaries (based on data from the companies) at a national level?