PART A. How much water do I use?
Measure your own personal water use over a period of 7 days, using the spreadsheet provided. You will derive a personal average daily water use for each purpose, as well as a total personal daily water use, in L/day.
For the written assignment include the following information in approximately 2 – 2 ½ pages:
- The table showing your direct water use and calculations for the 7 day period
- An analysis of your average daily use, including % used for each purpose
- A comparison of your average daily water use, to the average for Christchurch of 435 L/person/day
- Consider how your water use may change if you were to measure this in summer
- Consider how you could most effectively reduce your water use
PART B. Where does my water come from?
Depending on where you live around the Christchurch or Lincoln area, your domestic water comes from a different part of the unconfined, or confined, aquifer system. Most of the domestic water wells in the urban area access groundwater in the two shallowest aquifer levels (aquifer 1 and aquifer 2). In the Selwyn district, both unconfined (such as the Springston Gravels aquifer) and deeper confined aquifers system providing domestic water.
The conductivity of the water can provide a indication of the source of this water; if it is largely recharged by the Waimakariri River, it usually has a conductivity of <150 µS/cm (can be written as <15mS/m), and if it is mainly recharged by rainfall in the catchment, as in the southern or northeastern part of the area (see Fig 1.3 below), it will have a conductivity of between 150µS/cm and 300 µS/cm (15-30mS/m). There is a useful introduction to this in the opening pages of the ECan (2002) report on groundwater quality in this region (on LEARN).
For the written assignment include the following information in approximately 1 ½ pages:
- The conductivity of your tap water (bring a sample of your tap water, in a well rinsed (3 times), clean container of more than 100 mls on the fieldtrip, to measure this).
- An analysis of where your tap water may be coming from (aquifer and recharge source), given its conductivity and your understanding of the aquifer system, as discussed in lectures and described at the beginning of the ECan (2002) report. Include a brief summary of key aspects of the aquifer system as part of your answer.
- Consider how old your water may be (again based mainly on the ECan (2002) report).
PART C. How does it get to me?
It takes a considerable amount of infrastructure, resources and money to get domestic water from the ground to your tap. Information provided on the fieldtrips and information available via council websites will help you answer this part of the assignment
For the written assignment include the following information in approximately 1 ½ pages:
- A description of the infrastructure and processes that are used to get clean and safe drinking water to your tap
- An estimate of the cost of this infrastructure
- Does all domestic water need to be of drinking water quality? Justify your answer and note steps that could be taken to reduce your use of high quality groundwater.
PART D. What are the effects of my direct water use on the resource?
Finally you need to consider what would have happened to the water you use, if it had not been extracted from the system for delivery to your household, and what happens to the water after you have used it.
For the written assignment include the following information in approximately 1 ½ pages:
- Consider the natural fate of groundwater in these aquifer systems and how it interacts with surface water systems
- What surface water features might be affected by taking water from the groundwater system?
- Are these surface water features currently valued? What purpose do they serve (think about natural environmental processes as well as human uses)
- Consider what happens to water when it leaves your household, and how it affects the natural environment it is discharged to.
Key Reference:
ECan 2002. Christchurch-West Melton Groundwater Quality: A review of groundwater quality monitoring data from January 1986 to March 2002. ECan Report No. U02/47
