Incredible, we have a house meter and I have had a sub meter fitted, I have arranged with southern water a non return to sewer charge for the business. For example if our house uses 75 cubic meters of water we will be billed for that, I then read my sub meter and submit the reading for example 45 cubic meters. The bill is then re calculated and basically the difference is what the business. pays. So 75 - 45 = 30 You have to read you sub meter regular at least once a week.