Mr. Douglas Millican:

The second category of discount is for single occupiers of a property who receive a 25% discount. That is a proxy for the fact that they will use less water. The cost impact of marginal increases or decreases in water usage for a company involved in running a wastewater business is really small. The big costs derive from the fixed provision of infrastructure to provide and take away wastewater.

A big element, certainly in the system in Scotland, is the cost of taking away and treating rainwater that feeds into a combined sewerage system. In large part, the charging system we have reflects that fixed cost nature of our business.