Marae water usage monitoring update

NIWA has partnered with ten marae around the North Island to monitor water (as a surrogate for wastewater production) and marae usage.

The project seeks to refine design assumptions for water and wastewater system designers, and enable the potential benefits of a range of innovations to be assessed (e.g., installation of water-efficient showers, toilets, taps and appliances, and separate treatment of blackwater and greywater).

Monitoring at some marae has been underway for over 12 months while at others it has only recently started. Interim monitoring results from three marae show a good correlation between water use and marae occupancy (Figure 5). The monitoring results illustrate the extreme variability in marae usage, with little to no usage occurring for extended periods of time coupled with short periods of high use.

Typical wastewater system design guidelines suggest per capita wastewater generation of 40 litres per person per day (l/p/d) for day-only marae users and 150 (l/p/d) for day and overnight marae users.  While limited conclusions can be drawn at this early stage, it appears that actual per capita water usage, and therefore wastewater generation, is lower than typically assumed in marae water and wastewater system design.

The initial monitoring results suggest that existing design guidelines need to be reviewed and confirms the benefits of recording marae occupancy and measuring water use to inform better water system management and design. The findings of the monitoring programme will be published following analysis of all data from the monitoring project.

Reference:

Colliar, J.M., Sukias, J.P., Tanner, C. Stott, R. Bellingham, M. (2015) A marae water use monitoring network: Preliminary assessment of water use. New Zealand Land Treatment Collective Conference 2015, Wanaka, New Zealand 25 – 27 March. 

Contact

JACKIE COLLIAR
Environmental Engineer
jackie.colliar@niwa.co.nz or Jackie.Colliar@gmail.com

Location of marae participating in the water usage monitoring project. [NIWA]
Figure 5 (Marae 1): Three months of occupancy (day only and day and overnight) and total site water usage data - Data shows regular marae usage. There is a good correlation between total site water usage and recorded occupancy with peak occupancy of 200 people (162 during the day only & 38 during the day and overnight) coinciding with peak daily water usage of 4,600 litres. [NIWA]
Figure 5 (Marae 2): Three months of occupancy (day only and day and overnight) and total site water usage data - Data shows regular marae usage. There is a reasonable correlation between site water usage and recorded occupancy. Peak daily water use of approx. 9000 litres coincided with recorded occupancy of 200 (140 during the day only 60 during the day and overnight which was the second highest number of occupants recorded). Peak recorded occupancy of 260 people (160 during the day only 50 during the day and overnight) coincided with daily water use of approx. 8500 litres (which was the second largest daily water volume recorded). Recorded water flow during periods of no recorded occupancy suggests reasonably high levels of water leakage. [NIWA]
Figure 5 (Marae 3): Three months of occupancy (day only and day and overnight) and total site water usage data - Data shows relatively infrequent marae usage with one major event recorded. There is a good correlation between site water usage and recorded occupancy with peak occupancy of 150 people coinciding with peak daily water usage of 4, 400 litres. Data also suggests very little water leakage from the site water reticulation system. [NIWA]