Compost Toilet Trial Report - Ministry of Civil Defence and ...

4.6 Water
Participants recorded their daily water use, excluding water for hand washing, in the
diaries (Appendix 9). They were also asked about their water use at site visits
(Appendix 7) and in the surveys (Appendix 10). The results for these were
comparable, though the site visit information was the most comprehensive.
The average daily water used is shown in Graph 4.4. The orange trend line is
calculated for all participants; while the green trend line is with the outlier (Participant
K) removed to better show average expected water use.
Graph 4.4 shows that water use per person, per day does vary, but a minimum of 1
litre per person per day is required, and a more conservative recommendation would
be 2 litres per person per day. This is solely for using and cleaning the system.
Many of the participants voluntarily limited their water use, so as to better replicate an
emergency situation. One participant collected rain water (Figure 4.12) and used that
as their only source of cleaning and diluting urine.
While the compost toilets use little water in comparison to normal flush toilets (a dual
flush system averages 3 to 6 litres per flush); they do rely on the user having a store
or supply of water to use in the toilet. The Ministry of Emergency Management and
Civil Defence currently recommends that a household stores drinking water for at least
three days and recommends at least three litres/per person/per day
(www.getthru.govt.nz).
Figure 4.12: A selection of vessels set up
to collect rain water from the participant’s
roof
Any promotion of the compost toilet as part of a household’s emergency kit will need
to include the provision for storing additional water, noting that the water does not
need to be of drinking water quality.
Allow 2 litres of water per person per day, noting that some users may need
additional amounts.
Users will need to consider the need to access or store additional water to use the
compost toilet in an emergency.
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