Metered billing

For capacity, both electricity and gas billing can vary over time. A meter for either of those sources usually has a “demand” dial, that measures the highest demand for the period, and resets to zero once the meter is read. Demand is then billed at the highest level as registered over a rolling N-month period. For water however the size of the pipe does not vary, and is not measured by a meter, so the capacity charge is fixed. Nevertheless in commercial and particularly industrial water billing a two-register meter (sometimes known as a “combo” meter) is included, with capacity and usage measured separately depending on whether a high or low flow of water is passing through.