After my recent expansion it is needless to say that my water bill (metered) has gone up however as i only get a 6 monthly bill it is always a shock when i get it but i just got one for £703.62 
Anyway i have always feared telling the water board that we are window cleaners due to some FALSE information that i read on here that w/c'ers would get charged commercial rates as opposed to domestic rates so dont tell them regardless of the discount you would get for lowered sewerage costs. The water company told me today that this is false and you pay for the water that you uses whether you are commercial or domestic , so all you metered wfp'ers you must contact your water company and claim back your sewerage costs i think mine is around 25% , so at my current spend i will save £350 per year!! 
do you have meters on your ro ?, I asked about this when I changed mine to commercial use, what I got was an increase in charges for what being honest,. Don't be fooled into thinking they want to help you, they want there pound of flesh simple as imo
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c'mon then give details , i dont think there is any propaganda here , them against us etc!! :
tHE CHARGE FOR WATER IS HIGHER FOR COMMERCIAL USE. TRYING TO CLAIM against sewage charge, what area do you work in ? I said cambridgeshire, there reply@: so your water goes down our sewers, I said I also work in bedofrdshire, and london, they said if you can prove the water is not used in there area they would refund the sweage charge, as long as the other company you use know that you a using water for commercial sweage and they charge you.
In other words pay the bill and stop moaning is the point I got. I found this out when all was going on about the water companies saying about banning wfp in a drought order, I called them up and asked the questions in regards to loads of things.
Hope that was me that needed to answer.
Ian