In late July 2017, the Shoprite Act for Change team gave BridgIoT the go-ahead to pilot a water-saving technology at two schools, one of which, was Hector Peterson Secondary School in Wallacedene. Hector Peterson is a zero-fee (section 20) school with over 1200 students.
In August 2017, meetings were held with the principal of Hector Peterson, Mr Mavovana, and a smart water meter was installed to monitor water consumption data. The principal was interested in the water saving technology since the school had a big utility bill. This was the very first school installation of a Dropula running entirely on batteries and using Sqwidnet’s new Sigfox wireless technology.
The average consumption per weekday for the school was measured to be 47 kL, while the average weekend day’s usage was measured to be 37 kL. The minimum nightly flow (MNF), between 01:00 and 04:00, was found to be 2.3 kL/hr, and 1.4 kL during the weekend daytime. The flow peaked at 2.5 kL/hr during weekdays. There was very little variation in the flow, indicating that the school had significant leakages/losses.
On the 1st of September 2017, the BridgIoT team visited the school to inspect the plumbing and to determine where the water was being lost. It was clear that the toilets and leaky valves were the main problems, with about 20 of the 40 toilets malfunctioning. Problems ranged from flushers that were stuck open, to float arms that were bent and that could never close.
On the 12th of September 2017, the plumbing work was completed by an eager CBD Plumbing to replace the plumbing of 20 of the toilets and to replace the faulty valves. Immediately following the installation, the peak weekday flow rate dropped to 1.28 kL/hr, with the valves open (a reduction of 49 %). Since the complete intervention, the consumption dropped to 13 kL per weekday, a 72 % reduction for weekdays, and 100 % reduction for weekend days (providing the responsible persons remember to close the stopcock). With these reductions, the monthly bill will reduce by ~R 46 000 /month. Included here is a picture of one of the toilet cisterns leaking before the plumbing intervention.
The final step was a behavioural intervention, in which the principal and children were given access to the consumption information, including daily consumption, MNF losses, and time-of-use consumption information. After this information was introduced, the consumption dropped to an average of 4 kL /weekday, but then increased slightly and stabilised at 7 kL /day on average. This amounts to a total saving in excess of R 50,000 per month.
A weekday (22 August 2017) before intervention (52 kL/day). Notice the y-axis is at 2500 litres.
Weekday (13 September 2017) during application of intervention (13 kL/day). Notice the y-axis is at 2200 litres.
Weekday (27 September 2017) after final intervention (4 kL/day). Notice the y-axis is at 600 litres.
Author: Thinus Booysen
Editor: Arno Scholtz