Simply put, a “water footprint” is a numeric representation of water usage. Many types of water footprinting tools are available; each is designed to measure water usage in some capacity. Water usage can be measured many ways, so not all of the tools are the same, and each one serves a specific purpose. For example, some focus on volumetric measurements, others focus on quality parameters.
That’s why choosing the right tool is important. When people want to measure temperature, they use a thermometer. When they want to measure weight, they use a scale. Measuring water usage is no different – so it’s important to pick the appropriate tool for the job.
Tools should be selected based on what information is available, what information the user is seeking, and what the user intends to do with the information.