Where Does Water Fit in?

Abstract

In this chapter we examine the problem of water scarcity and water security and how this will be affected by global warming. The idea that water is a peak resource is explored as is the use of water footprinting.

Homework?

Well, just how much water do we use individually or as a family? Using the ‘mywaterdiary’ template above, or the app, calculate your water usage for a full week. This will help you identify what activities use the most water in your household. What are the key things you can do to reduce your water usage? Also complete an online your water footprint: http://www.waterfootprint.org/?page=cal/WaterFootprintCalculator.

What percentage of your water footprint is your actual direct water use as measured by your water diary?

Finally try and find out how much water your own appliances use and see how they compare to the more efficient models available. Showers and taps are easy to measure using small container. Just time how long in seconds it takes to fill your container then calculate the volume. The easiest way to do this is to use digital kitchen scales. Weight the container empty. Then reweigh when it has the water present in grams. Subtract the weight of the container to give you the weight of water and as 1 L of water weighs exactly 1 kg, then a gram of water is 1 millilitre (mL).

An example is given below where water was collected from my cold tap in the kitchen. The flow was measured when the tap was partially turned on and when fully turned on. Water was collected for exactly 5 s. You can do the same with your shower, with care. If you want to get a really accurate measure you need to collect water in a larger container for a longer period, say 15 s and then take an average of three or four readings.

• The weight of the empty container was 104 g

• Weight of the container plus water collected for 5 s:

  • Tap partially on: 596 g

  • Tap fully on: 1399 g

• Subtract the weight of the empty container and then multiply by 12 to convert the flow into grams per minute.

  • Tap partially on : 596 – 104 = 492 492 × 12 = 5904 g

  • Tap fully on: 1399 – 104 = 1235 1235 × 12 = 14,820 g

• As 1000 g is a kilogram and 1 kg is equivalent to 1 L of water, then our water use is:

  • Tap partially on uses 5.9 L per minute

  • Tap fully on uses 14.8 L per minute