Abstr x Cact

In the quantification of grey water footprint, there is a product: Abstr x Cact. What exactly does this product indicate? For example, if you have abstracted a volume of water from a lake and you have used this for cleaning purposes in a factory, this amount of water x the actual conctentartion should be abstracted from the product Effl x Ceffl? Can you please provide me with an example?

Thank you