Monitors in showers, which display how much water is being used and sound an alarm when a limit is reached, have significantly cut water consumption in household trials. The immediate feedback from the alarm monitor made consumers more aware of their behaviour, which they could then modify.
Water resources around the world are under pressure from a growing global population. In addition, climate change is predicted to affect water resources, which is especially serious in countries with a dry climate, such as countries bordering the Mediterranean. It is recognised that human behaviour can have a significant impact on strategies designed to manage water sustainably.
The study compared the water consumption of shower-users before and after the installation of a shower monitor in households in Australia. The shower monitor displayed the amount of water being consumed and had an alarm to signal when a predetermined amount of water had been used.
151 households were fitted with smart water meters to log water consumption data which captured the duration, volume and flow rates of shower use, as well as all other water uses (e.g. washing machine, dishwasher). 44 of these households then had shower monitors fitted which were set to sound an alarm when 40 litres (l) had been used (allowing a 5 minute shower with a flow rate of 8 litres a minute).
Among the results, the study showed that without the monitors, the average household water consumption of the 151 households was 157.2 l per person per day. On average, each person consumed one third of this amount of water when showering.
Overall, the alarm monitor helped reduce the average volume of water per shower to nearly 40 l (the target). The average shower volume fell from 57.37 l to 41.97 l after installation of the shower monitor, saving 15.40 l, or 27 % water for the average shower. Water-conscious shower users especially modified their behaviour, with many of the 30-40 l showers falling to just 10-20 l.
The average shower time fell from 7.19 to 5.86 minutes, a reduction of 1 min and 20 seconds or 18.6 % in the 44 households fitted with the monitors. Although this indicates the shower monitor was effective in reducing the time people spent in the shower, many people still continued showering after the alarm went off. Some householders realised that a slower flow rate could extend the time in the shower before the alarm sounded, indicating that the monitor was able to modify their shower behaviour.
In addition, the study calculated that 1.5 gigalitres or 3 % of the total city water consumption could be saved if all 200,000 households in the trial city installed shower monitors. Savings in energy required to heat the hot water for the showers were estimated for a range of heating systems. These calculations suggest that fitting shower monitors could potentially save up to 2.4 % of the total city energy consumption each year. Due to savings in water and energy costs for the consumer, the payback period (return on the investment) for the monitor was estimated to be 1.65 years.
Source: Willis, R.M., Stewart, R.A., Panuwatwanich, K. et al. (2010). Alarming visual display monitors affecting shower end use water and energy conservation in Australian residential households. Resources, Conservation and Recycling. 54: 1117-1127.