Analysis Part 1: Analyzing the Water Efficiency of Your Local Water Treatment and Distribution Systems
You have calculated the water footprint of your community and its tap water using real information that you found from your research but you may now be wondering how different these footprints might have been if some things in your community or at your treatment facility were different. You can use the calculations process you learned to test different changes and see how they could affect your footprint values.
Try making the changes described below and calculate how the values for your community water footprint and footprint of each litre of tap water would change. Keep track of the results of each change by recording them in a table.
- Increase the water efficiency of the treatment process. The facility will still need to output the same amount of water but it can now do that while bringing in less freshwater.
You can simulate this by lowering the value for amount of water entering the facility, bringing it closer to the amount of water entering distribution.
- Stop creating wastewater during the treatment process. If the water used by the facility does not need to be treated as wastewater less fresh water will be used.If your local drinking water treatment facility does not produce wastewater then skip this step or change it to see how much larger your community’s water footprint could be if this was the case.
- Increase the water efficiency of the distribution system. The same amount of tap water will be used but since less water is lost in distribution the facility does not need to produce as much treated water.
This can be simulated by lowering the amount of water entering distribution, bringing it closer to the amount of metered water used. As you lower the amount of water entering distribution you should also lower the amount of water entering the facility by the same amount. (Water entering facility minus water entering distribution should be constant.)
Optional: For more accurate results you could keep the proportion of water entering the facility to water entering distribution constant rather than keeping their difference constant.
For example, consider a treatment facility that brings in 100L/s fresh water and puts 96L/s treated water into a distribution system that loses 22L/s. If the distribution system is improved so that it loses only 10L/s instead of 22L/s then the treatment facility will need to produce 12L/s less treated water than it did before. (96L/s – 12L/s = 84L/s) So if the treatment facility needs to put 84L/s into distribution how much fresh water does it need to bring in? You can find this by looking at the proportion of water entering the facility to water entering distribution.
96L/s / 100L/s = 84L/s / xL/s
(96*x)L/s = 8400L/s
x = 87.5L/s
The amount of fresh water entering the facility should be decreased to 87.5L/s
- Increase the water efficiency of the people in the community. If people use less tap water then less treated water will need to be produced.
This can be simulated by lowering the values for metered water used, water entering distribution and water entering the facility all by the same amount.
Optional: For more accurate results you could Decrease the amounts of metered water used, water entering distribution and water entering the facility proportionally rather than decreasing them by the same amount. You can do this in a similar way as the example in question 3.
- Try out different combinations of the previous four steps.