Source
https://www.phfscience.nz/media/tr0hiabi/esr-scoping-study-composting-toilets-new-zealand.pdf — original source (opens in a new tab; the file is not redistributed)
Humphries et al. (2022) — Composting Toilets in New Zealand: A Scoping Study
NZ Ministry of Health / ESR scoping study of composting (waterless) toilets — the authoritative NZ regulatory + performance basis the URL_009 vendor page lacked. Gives the AS/NZS 1546.2:2008 end-product-quality thresholds and burial rule (6–12 months, ≥100 mm soil), the 15–28% indoor household water saving vs flush, the fragmented national consenting picture (no consistent pathway; discharge-consent vs permitted-activity split), a June-2022 list of NZ commercial suppliers (incl. Clivus Multrum/WCTNZ, Nature Loo, Rota-Loo, Nature's Head/OGO), and rich qualitative material on Māori waste tikanga and social acceptability.
Grey literature — ESR client report (FW 24031) for the Ministry of Health, informed by a literature review (1986–2022) and an online survey of 19 regulatory/public-health stakeholders. Primary read, figures verbatim →
data_quality: verified. ⚠ It does NOT give per-model technical specs (capacity per persons/uses-day, compost yield, removal interval) or any composting-toilet installed cost — only a conventional on-site-wastewater comparator cost (15,000–40,000) that composting toilets undercut. So RT_223 is advanced, not resolved: the vendor spec sheets are still needed for the D03 sizing/cost cell.
Summary
This is a scoping study of composting (waterless) toilets in New Zealand, prepared by the Institute of Environmental Science and Research (ESR) for the Ministry of Health (June 2022, Client Report FW 24031). It draws on a literature review (peer-reviewed and grey literature, web searches 1986–2022) and an online survey of 19 stakeholders (8 Regional Councils, 1 Government Department, 5 District/Unitary Councils, 3 Public Health Units/DHBs, 2 industry consultants). Its focus is the public-health issues and the policy/consenting environment around composting toilets, not their engineering design — the report explicitly excludes greywater and conventional on-site wastewater, and notes AS/NZS 1546.2:2008 itself carries no design guidance.
For Neobiome Intelligence this is the document that resolves the regulatory and water-saving legs of RT_223 (which URL_009, a vendor marketing page, could not): it sets out the AS/NZS 1546.2 end-product-quality criteria and the 6–12-month/100 mm burial rule, the 15–28% indoor household water saving, the optimum biophysical composting conditions (moisture 50–60%, temperature 40–65°C, C:N 25–35, pH 5.5–8.0, porosity 35–50%), and the fragmented NZ consenting landscape. It also supplies a June-2022 census of NZ commercial suppliers. It does not supply per-model capacity/yield/cost specifications or a composting-toilet installed cost (only the 15k–40k conventional on-site-wastewater comparator), so the D03 sizing/cost cell still needs the manufacturer datasheets — RT_223 stays open. For the thesis it offers substantial qualitative material on Māori tikanga around human waste (tapu/noa, discharge-to-land preference), social acceptability, the circular-economy/self-sufficiency framing, and disaster-resilience use (Christchurch/Kaikōura earthquakes).
Key claims
- claim: "Scope and method. 'This report provides a scoping study of composting toilets in New Zealand to identify the types of systems and the public health issues associated with their operation, maintenance, and waste disposal... Information on associated waste(water) practices, such as greywater are outside the scope of this report.' It is informed by a literature review (web-based searches 1986–2022 across ScienceDirect, Web of Science, PubMed, ProQuest Public Health, Google Scholar) and an online survey sent to approximately 60 individuals, of whom 19 responded: 8 Regional Councils, 1 Government Department, 5 District or Unitary Councils, 3 Public Health Units or District Health Boards, and 2 industry consultants."
source_location: "Executive Summary, p.1; Section 1.2, pp.3–4 (search engines/dates, ~60 sent); Section 3, p.21 (19 respondents breakdown)"
- claim: "Optimum biophysical conditions for composting human waste (Aburto-Medina et al 2020): aeration; moisture content of 50 – 60%; temperature 40 - 65°C; carbon to nitrogen ratio of 25/35; pH 5.5 – 8.0; porosity 35 – 50%. The process is aerobic thermophilic digestion (40–65°C)."
source_location: "Section 2.1.1, p.5 (repeated in Executive Summary, p.1)"
- claim: "AS/NZS 1546.2:2008 composted end-product quality requirements regarded as safe and ready for disposal (Table 2): Moisture < 75 % by weight (ASTM D4959-00); Total faecal (thermotolerant) coliforms < 200 MPN/g dry weight; Salmonella spp not detected in 4 g dry weight; Consistency — sample shall contain no recognisable faecal material; Colour — good compost is black; Odour — no offensive odours immediately following removal from the chamber."
source_location: "Table 2, p.15"
- claim: "AS/NZS 1546.2:2008 burial/disposal rule: 'The composted end product is to be buried in soil for 6-12 months, with at least 100 mm covering of soil, where it will not come into contact with consumable plants or surface water (Appendix K, AS/NZS 1546.2:2008). Access to the area needs to be restricted. If burial is not authorised by a regulatory authority it needs to be removed for disposal in a manner approved by the regulatory authority.' AS/NZS 1546.2 also requires burial of composted faecal material at a soil depth greater than 100 mm to minimise pathogen risk before use as a soil conditioner."
source_location: "Section 2.4, pp.15–16 (also Section 2.1.2, p.8; Section 2.1.1, p.6)"
- claim: "Water saving: 'Composting toilets require no or minimal (if handwashing is considered) water usage and save between 15 – 28% in indoor household water use and therefore provide a water conservation alternative to traditional forms of human wastewater management (Salmon et al 2004).'"
source_location: "Section 2.1.7 Environmental effects, p.14 (report attributes the 15–28% figure to Salmon et al 2004)"
- claim: "Capacity / emptying threshold (survey respondent): 'if a composting toilet is utilised by more than 4 people the system requires frequent emptying (i.e., daily) into a secondary composting pile or chamber to enable decomposition to occur over time.' The report gives no per-model capacity in persons or uses per day."
source_location: "Section 3, Operation and Maintenance, p.25"
- claim: "Conventional on-site-wastewater comparator cost (NOT a composting-toilet cost): 'In a rural setting where on-site wastewater management systems can range from $15,000 - $40,000 (pers comm Andrew Dakers and Fiona Ambury, 10 June 2022) to design and install along with annual maintenance and operation fees, composting toilets may be considered an attractive financial alternative.' ⚠ This $15k–$40k band is the cost of a conventional/septic on-site wastewater system — the comparator composting toilets are said to undercut — NOT an installed cost for a composting toilet, which the report does not provide."
source_location: "Section 2.2, p.11 (pers comm Dakers & Ambury, 10 June 2022)"
- claim: "Storage / maturation times for pathogen die-off. Faeces 'can be safely used as a fertilizer after storage either at ambient temperatures for two years or composting at high temperatures for six months (Kaczala 2006)'. WHO (2006) household-level guidance: storage should be more than 1 year above 20°C and up to 2 years at 2-20°C; alkaline treatment must last more than 6 months at pH > 9, at 35°C, with < 25% moisture. WHO Table 4: storage at 2–20°C for 1.5–2 years, or >20–35°C for >1 year."
source_location: "Section 2.1.3 Duration, p.10; Table 4, p.17 (attributed to Kaczala 2006, WHO 2006, Gajurel and Wendland 2004)"
- claim: "Pathogen inactivation vs NZ climate: 'a compost temperature greater than 50˚C is required to inactivate or destroy pathogens (Nasri et al 2019)'; 3-4 months is inadequate and greater than 12 months is more appropriate (Mehl et al 2011). In New Zealand's temperate climate thermophilic conditions will often not be achieved or only briefly, so 'the composted product should be treated as hazardous until it has been buried for 6-12 months.'"
source_location: "Section 2.3.1 Pathogens, p.12; Section 2.1.1, p.6; Section 4 Discussion, pp.27–28"
- claim: "Carbon deficiency of faeces: 'The ratio of carbon to nitrogen (C:N) required for composting is between 25 to 35. Human faeces are normally deficient in carbon, with a typical C:N ratio of 8. To facilitate composting, an additional carbon source is required (Depledge 1997).' Suitable carbon bulking agents: wood shavings, grass and leaves, sawdust, toilet paper and straw."
source_location: "Section 2.1.3 Ratio of carbon to nitrogen, p.10"
- claim: "System types: two main types of waterless composting toilet — continuous (single chamber; waste received under the pedestal until composting is complete or the system is full) and batch (a container/bucket moved outside to decompose when full and replaced by an empty one). Both may be further categorised by urine diversion or not. Urine 'only needs to be held in an enclosed container for a period of time (6 months)' to sanitise; urine diversion reduces odour and excess liquid. If urine diversion is used, AS/NZS 1546.2 requires the urine/liquid to go to an on-site wastewater system meeting AS/NZS 1547:2012."
source_location: "Section 2.1.2, pp.6–8; Section 2.4 Note, p.15"
- claim: "Commercially available composting toilets in New Zealand as of June 2022 (Appendix A.1): Bambooloo; Bioloo (Sun-Mar Spacesaver / Mobile / Excel); Enviro Composting Toilets (Aquatron, Farmstyle/Back Country); Green Loo (Rota-Loo 650, 950, 2000); Green Earth (RV Pod, Eco Pod 44, Scandi Pod, Kiwi Pod); Simple Waste Water Solutions (Short Drop Toilet – Basic/Deluxe); Toilets NZ (Nature's Head and OGO); Waterless Composting Toilets NZ Limited / WCTNZ (Clivus Multrum CM Low Profile, Nature Loo Classic 650, Sun-Mar GTG, Nature Loo Mini, Bambooloo); Zing Bokashi (Nature Loo range, Clivus Multrum CM2)."
source_location: "Appendix A.1, p.35"
- claim: "Regulatory framework. Composting toilets are governed by AS/NZS 1546.2:2008 (waterless composting toilets — performance statements, evaluation tests, operation/maintenance; the standard carries NO design guidance and should be read alongside AS/NZS 1547:2012 on-site domestic wastewater). They must also comply with the Building Act 2004 and Building Code (clauses B1, B2, G1, G14 for structure, durability and hygiene; G12, G13 for plumbing/foul water), the Resource Management Act 1991 (a resource/discharge consent may be required), and the Health Act 1956 (Section 54, Schedule 3 — nightsoil collection and disposal is an 'offensive trade' requiring authorisation by the territorial local authority and the Medical Officer of Health). Composting toilets 'can only be used in areas where mains sewerage system is not available... unless the building consent authority provides a waiver'."
source_location: "Section 2.4, p.16; Section 3 Policies and legislation, pp.22–23"
- claim: "Consenting inconsistency: 'within New Zealand there is not a consistent approach to composting toilet consenting with no clear pathway for compliance with national standards.' Some councils require a discharge consent to apply composted human waste to land; others treat it as a permitted activity. 'Very few commercially available composting toilet systems have documentation to demonstrate compliance with Australia/New Zealand Standard 1546.2:2008.' The most consistently cited supporting guidance is Auckland's TP58 (2004), now superseded by GD06 (2021)."
source_location: "Executive Summary, pp.1–2; Section 3 Consent and compliance, p.24 (TP58/GD06 at Section 3, p.22)"
- claim: "Māori values (thesis): 'It is a commonly held view amongst Māori that the discharge of human waste to water is unacceptable regardless of the level of treatment and that discharge of human wastewater to land is to be encouraged.' Human excreta is tapu; land is the medium by which tapu is made noa. 'The literature review could not find a specific reference to the use of composting toilet waste from a Māori perspective', though a consistent theme is separation between the human food chain and human waste streams."
source_location: "Section 2.6 Māori Values and Social Acceptability, pp.18–19"
- claim: "Disaster-resilience use and a NZ Clivus case. Composting toilets were used during the Christchurch (2011) and Kaikōura (2016) earthquakes; in Christchurch 'reticulated wastewater was not fully restored for 3 years post the February 2011 earthquake.' At the Landcare Research Tamaki building (Auckland), seven individual toilet pedestals were connected to two Clivus Multrum composting bins using no water for flushing; as organic material decomposes 'it reduces in volume by up to 90%'; in June 2007, '78% of staff said that they were completely or beyond satisfied' after 3 years of operation."
source_location: "Section 2.2, p.11 (earthquakes); Appendix B, p.36 (Landcare Research case, Trowsdale et al 2011)"
- claim: "Social acceptability: a survey in Hawaii showed 'more than 60% are willing to pay extra for the UDDT, while only 22% knew that such systems existed' (Lamichhane & Babcock Jr 2013). In New Zealand composting toilets 'have gone through several phases of popularity' and, while often perceived as environmentally friendly, 'some people have a less favourable view of the need for storing and emptying composted human excrement' (Chen & Roberts 2021)."
source_location: "Section 2.7 Social acceptability of composting toilets around the world, pp.19–20"Neobiome Intelligence relevance
context: both — the NI value is the D03 (Water, Waste & Circular) sanitation cell; the thesis value is the qualitative Māori / acceptability / resilience material. It feeds d03_water_waste_circular and is the authoritative NZ backing the URL_009 vendor page could not supply.
- The AS/NZS 1546.2 compliance gate for a D03 composting-toilet deployment (D03). The report holds the end-product-quality thresholds (moisture < 75%, faecal coliforms < 200 MPN/g dry weight, Salmonella not detected in 4 g) and the disposal rule (bury 6–12 months under ≥100 mm soil, restricted access, no contact with consumable plants/surface water, or remove by an authorised contractor). This is the pass/fail gate any waterless-sanitation option in the model must clear, and it pairs with the wider on-site-wastewater regulatory stack in REG_013 and CR_046.
- The water-demand-reduction lever (D03 water balance). Composting toilets save 15–28% of indoor household water use vs flush — a concrete demand-side reduction that feeds the D03 water-balance/self-sufficiency cell alongside the residential-water baselines in OT_036, and complements rainwater/greywater supply sources (OT_039, OT_040). It closes the water-savings leg of RT_223.
- ⚠ Cost cell still open — only a conventional comparator, not a composting-toilet cost. The report gives no composting-toilet installed cost; its only figure is the
15,000–40,000 cost of a conventional on-site wastewater (septic) system that composting toilets are said to undercut (pers comm Dakers & Ambury). That comparator corroborates the NZ on-site-wastewater cost band already held in CR_048 (the RT_278 septic-cost cell), but the composting-toilet CapEx itself remains a gap requiring the manufacturer datasheets. - Capacity is only a coarse threshold. The single sizing datum is the survey note that > 4 people ⇒ daily emptying into a secondary pile/chamber. No per-model persons/uses-per-day, compost yield, or removal-interval figure is provided — so the model cannot yet size a specific unit from this source.
- Consenting is a real feasibility/permitting risk for D03. The report’s headline finding is that NZ has no consistent consenting pathway — some councils require a discharge consent to apply composted waste to land, others treat it as a permitted activity, and very few marketed systems document AS/NZS 1546.2 compliance. For an SSI “sanitation self-sufficiency” claim this is a live permitting-risk flag, not a solved problem (pairs with CR_046 and REG_012).
- Scope caveat (management-intensity). In NZ’s temperate climate thermophilic composting temperatures (>50°C) are rarely sustained, so the end product must be treated as hazardous until buried 6–12 months, and systems need active user operation and maintenance. Composting toilets are a genuine D03 waterless-sanitation option, but a management-intensive one — not a set-and-forget appliance — which should temper any headline self-sufficiency benefit.
Thesis relevance (context: both). Section 2.6 on Māori tikanga around human waste (excreta as tapu; discharge-to-water rejected regardless of treatment; discharge-to-land / whakanoa preferred; the Wellington ‘Living Earth’ biosolids case) is directly usable for the thesis threads on mātauranga Māori and co-governance (topic maori). Sections 2.2, 2.7 and Appendix B give social-acceptability and disaster-resilience material (Christchurch/Kaikōura emergency use; Hawaii willingness-to-pay; Landcare Research 78% satisfaction) for the community-resilience and behavioural-acceptance argument, and the circular-economy/self-sufficiency framing (closed-loop nutrient return, off-grid independence) sits with LIT_022 and the eco-cycle thread.
Research targets
RT_223 — ADVANCED / PARTIAL (keep open)
This page advances but does not resolve RT_223. RT_223 sought composting-toilet technical + cost specifications for NZ (capacity persons/uses per day, compost yield + removal interval, water savings vs flush, installed cost, AS/NZS 1546.2, and Tasman District Council consent treatment).
Delivered by this source:
- AS/NZS 1546.2 requirements — end-product-quality thresholds, 6–12-month/100 mm burial rule, testing regime, standard objectives. ✅
- Water savings vs flush — 15–28% of indoor household water use. ✅
- National consenting picture — inconsistent; discharge-consent vs permitted-activity split; few systems documented AS/NZS-compliant. ✅
- Commercial-availability census (Appendix A, June 2022) — the NZ supplier/model landscape to target for datasheets. ✅
- Coarse capacity threshold — > 4 people ⇒ daily emptying. (partial)
Still missing (residual → RT_223 stays open, annotated PARTIAL; the residual is the retrieval of the manufacturer datasheets):
- Per-model technical specs — capacity in persons/uses per day, compost yield, removal interval — from the Appendix-A NZ suppliers (WCTNZ / Clivus Multrum, Nature Loo, Rota-Loo/Green Loo, Nature’s Head/OGO, Green Earth pods).
- Composting-toilet installed cost — the report gives only the
15k–40k conventional on-site-wastewater comparator, not a composting-toilet CapEx; the datasheets/quotes above are the retrieval route. - Tasman District Council consent treatment — not delivered (the survey is anonymised, councils un-named). Note this leg is largely obsolete under the retired-pilot / national-scope decision; the national consenting picture is delivered in its place.
Research gaps (prose, not raised as an RT)
- The report itself flags a NZ knowledge gap on the efficacy of composting processes to inactivate pathogens and degrade chemicals under NZ’s temperate climate, and on the prevalence/types of composting toilets in use nationally. These are public-health-research gaps of lower NI priority (they do not feed a calculation cell) and are noted here rather than raised as a formal RT.
Notes
Primary read of the authentic ESR client report FW 24031 (June 2022), a Crown-research-institute report prepared for the Ministry of Health — grey literature, source_type: other (prefix ot). Read in full via pdftotext -layout; every cited figure is traceable to a precise page/section of the PDF, so data_quality: verified.
Provenance caveat: this is a scoping study, so a number of its quantitative statements are the report’s own citations of secondary sources — the 15–28% water saving is attributed to Salmon et al 2004, the 15k–40k conventional-system cost to pers comm Dakers & Ambury (10 June 2022), and the storage/maturation times to WHO 2006 / Kaczala 2006 / Gajurel & Wendland 2004. The report is the primary source for its summary of these, and each is flagged inline in the relevant key_claim; the AS/NZS 1546.2 end-product-quality and burial requirements are the report’s direct restatement of the Standard.
No DOI or confirmed public URL — the report is identified by its ESR client-report number (FW 24031); url: null rather than an invented link.
Cross-references: complements URL_009 (the spec-less Clivus vendor page that triggered RT_223); the 15k–40k comparator corroborates CR_048 (RT_278 septic-cost cell); the consenting findings pair with CR_046 and REG_012; the water-saving figure sits with OT_036. context: both — feeds D03 (NI sanitation) and thesis threads (Māori waste tikanga, social acceptability, circular economy, disaster resilience).
Connections
Links to
Referenced by
Sources (2): URL_009 · URL_026
EDT domains (1): D03: Water, Waste & Circular Systems