{"id":296934,"date":"2026-02-22T17:57:08","date_gmt":"2026-02-22T17:57:08","guid":{"rendered":"https:\/\/www.newsbeep.com\/nz\/296934\/"},"modified":"2026-02-22T17:57:08","modified_gmt":"2026-02-22T17:57:08","slug":"wellingtons-brown-tide-christchurchs-big-stink-aucklands-toxic-beaches-why-our-wastewater-nightmare-has-just-begun","status":"publish","type":"post","link":"https:\/\/www.newsbeep.com\/nz\/296934\/","title":{"rendered":"Wellington\u2019s brown tide, Christchurch\u2019s big stink, Auckland\u2019s toxic beaches: Why our wastewater nightmare has just begun"},"content":{"rendered":"

My great-great-grandfather \u00adcollected night soil, the historical euphemism for human excrement. He came after dark on his horse-drawn cart to collect the contents of Masterton\u2019s outhouses. Rules dictated the hours to avoid people smelling nasty odours, and manure depots were designated outside towns.<\/p>\n

\n It was a vital service. Before night
\n soil \u00adcollections started in the 1870s, open drains and backyard cesspits caused stench and disease. Collections tapered off in cities when sewerage systems were built around 1900.\n <\/p>\n

Then came flushing. That\u2019s remarkable luxury. About 60% of people on Earth still lack a home toilet that safely manages human waste. Nearly 900 million people still defecate in the open.<\/p>\n

We flush our muck to the sewage treatment plant, never thinking of it again. But we\u2019re about to. Wastewater, stormwater and drinking water collectively take a quarter to a third of council rates, a cost that will be separately invoiced to households under the pending \u201cLocal Water Done Well\u201d system (the coalition\u2019s replacement for Labour\u2019s Three Waters legislation).<\/p>\n

A brief explainer of what\u2019s in the pipes: wastewater sent to treatment plants includes sewage flushed down toilets, the contents of household sinks and showers and industrial discharges. Once treated, much of this waste is flushed into waterways.<\/p>\n

\"SludgeSludge remaining after treatment expensively fills landfills. Photo \/ Wastewater Services Limited<\/p>\n

The value of these out-of-sight, out-of-mind systems becomes obvious when they fail, as Wellington and Christchurch\u2019s big stink and pollution events reveal. But maintaining and future-proofing them is expensive and rarely wins votes. <\/p>\n

Putrid odours have plagued residents of Christchurch\u2019s eastern suburbs since a fire destroyed part of the Bromley wastewater plant in 2021. Residents have endured headaches, nausea, dizziness and throat, nose and eye irritation. In mid-February, those suburbs had to boil drinking water due to unrelated bacterial contamination. In Wellington, untreated wastewater is being piped into the sea after a \u201ccatastrophic\u201d failure at the Moa Pt treatment plant. In Auckland, heavy rain generally leads to \u201cno swimming\u201d notices due to sewage overflows into the harbours, despite billions being spent over decades separating stormwater and sewage pipes.<\/p>\n

Hence our predicament: new and upgraded sewage treatment plants are needed and lack of treatment capacity is stopping homes being built.<\/p>\n

The plot thickens. Sludge remaining after treatment expensively fills landfills, and it may increasingly \u2013 and controversially \u2013 turn up on land. Treated wastewater piped into freshwater rivers and the sea still contains nitrogen and phosphorus. Those are useful nutrients, but in already degraded waterways, they fuel plant growth that smothers aquatic creatures. To complicate things, we add novel filth to our filth \u2013 chemicals and heavy metals from food, household products, pharmaceuticals and industrial waste.<\/p>\n

Lower standards<\/p>\n

You\u2019d think we\u2019d be getting better at this, and cities indeed clean wastewater more thoroughly than ever. But in December, the government implemented new wastewater standards that in many cases downgrade the quality of treatment, particularly for discharge to the open ocean.<\/p>\n

Take, for example, Tauranga\u2019s treated wastewater. It\u2019s discharged 950m off a surfing and swimming beach between Mt Maunganui and Papamoa. Under the new standards, 11 times more Enterococci, a faecal bacteria, will be allowed to flow out of the pipe than current discharge consent conditions allow. Suspended solids can roughly double in quantity. Nationwide, allowable nitrogen limits are set so high that plants discharging to the open ocean won\u2019t have to remove any nitrogen.<\/p>\n

\"Christchurch\u2019sChristchurch\u2019s odour-prone Bromley wastewater treatment plant. Photo \/ Nicole Miller; Calypso Science<\/p>\n

Eliza Cowey, a senior wastewater engineer with a global consultancy but speaking in her personal capacity, says the standards \u201cregress open ocean discharge quality requirements to approximately what we had in Christchurch in the 1800s, with no ability to require better treatment in a consent. I have never seen anything like this globally.\u201d<\/p>\n

The standards will be compulsory in resource consents for public wastewater treatment plants as they are renewed \u2013 despite Local Government Minister Simon Watts saying Local Water Done Well provides \u201clocal choice on how it gets done\u201d. <\/p>\n

They aren\u2019t minimum standards \u2013 cleaning wastewater more thoroughly costs more, and associated new legislation says operators must choose the most cost-effective option over the plant\u2019s life. Places such as Tauranga could get around this because their existing equipment outperforms the standards. <\/p>\n

\u201cIn these cases, the most cost-effective option will be to continue to run these plants as they were designed,\u201d Sara McFall, head of systems and strategy at the Water Services Authority \u2013 Taumata Aro-wai, said in a statement. <\/p>\n

But councillors prioritising rates control could be tempted to cut costs, reducing discharge quality.<\/p>\n

Easing the way<\/p>\n

Until now, there have been no national standards for sewage treatment, so getting resource consent for plants has been bespoke, slow and often expensively held up in court. After all, who wants one next door or discharging into their local waterway? A fifth of plants are operating under expired consents.<\/p>\n

With most aspects of wastewater discharge now set in legislation, communities will be able to haggle only over plant locations and where and how much volume they discharge. The aim is to limit costs while lifting treatment levels for poorly performing plants. These tend to service smaller towns, and standards for them are slightly looser.<\/p>\n

\"FromFrom left: Lutra\u2019s David Romilly, Watercare\u2019s Rob Tinholt, Poipoia\u2019s Tina Porou. Photos \/ Supplied<\/p>\n

Small plants are often simple shallow ponds that settle solids and oxygenate the sewage, growing microbes to digest waste. Cities generally treat sewage more thoroughly, with multiple treatment steps. They screen, settle and aerate sewage, then kill pathogens. Some pass treated water through wetlands.<\/p>\n

There were pleas against much of what\u2019s in the standards. They came from parties including regional councils, wastewater industry body Water New Zealand and the Parliamentary Commissioner for the Environment. <\/p>\n

One was for no \u201cbacksliding\u201d, with the Waikato Regional Council submitting the standards \u201cshould at least hold discharge quality at the levels of stringency they are now. If not, then water quality across the region will deteriorate and the percentage of waterways experiencing significant adverse effects will only worsen.\u201d<\/p>\n

David Romilly, chief engineer at water consultancy Lutra, welcomes national standards. \u201cAt least everybody\u2019s using the same rule book and we can all have discussions about how to get the best outcome, even if these are the numbers we have to meet.\u201d But, he says, the standards are \u201cconcerning in some instances, and the industry is certainly not pleased with where they\u2019ve landed as a whole, especially when you look at them from an international benchmark. There\u2019s other parts of the world that are certainly more advanced in their water regulations. In the US, there is this thing called anti-backsliding \u2013 an anti-degradation clause that prohibits you from going backwards in your water quality.\u201d<\/p>\n

Beyond the pipe<\/p>\n

Treated wastewater isn\u2019t totally clean. Almost half of our treatment plants discharge to water, and those \u201creceiving environments\u201d are often in poor health. About half of Waikato\u2019s rivers are degraded by nitrogen and phosphorus. Nationwide, bacteria levels make two-thirds of river sites unswimmable. <\/p>\n

But the new standards limit contaminants only according to a waterway\u2019s type, such as open ocean, estuary or lake, not its health. They say consents cannot require the receiving water to be monitored and must last for 35 years, so discharge can continue even if water quality worsens.<\/p>\n

Basing standards only on end-of-pipe quality is abnormal in developed countries, says Romilly. \u201cIn the US, where I\u2019m from, it\u2019s more water quality-based regulations, where you look at what you\u2019re discharging into and assess the impacts of what the treatment plant would do to those receiving systems, and then you\u2019re regulated on that.\u201d Taumata Arowai commissioned technical advice that said the same.<\/p>\n

\"TheThe spread of untreated sewage off Wellington\u2019s Lyall Bay after the failure of the Moa Pt treatment plant. Photo \/ Nicole Miller;Calypso Science<\/p>\n

Some precious waterways, such as those in national parks are exempt from the standards, plus two areas covered by more recent Te Tiriti o Waitangi settlements. Lake Taup\u014d is not. Despite some $80 million of public money being spent to reduce nitrogen entering it, it receives T\u016brangi\u2019s treated wastewater to the ongoing objections of local hap\u016b. <\/p>\n

There are special arrangements protecting drinking water intakes and shellfish gathering. But in general, there\u2019s little prominence given to M\u0101ori values, which call for the highest possible treatment standards and ongoing involvement with decision-making.<\/p>\n

The new standards also change rules for overflows, a nationwide problem in which raw sewage flows to water or land as a result of blockages or heavy rain overwhelming pipes. There are thousands each year, some caused by flushed wet wipes and \u201cfatbergs\u201d from fat and oil going down sinks. North of Auckland city, Warkworth\u2019s regular sewage overflows require oyster farmers in the nearby harbour to stop harvesting for 28 days each time.<\/p>\n

Councils currently need resource consent for overflows, but soon they won\u2019t. For overflows, the standards primarily require better monitoring and reporting.<\/p>\n

Tina Porou (Ng\u0101ti Porou, Ng\u0101ti T\u016bwharetoa), founder of resource management consultancy Poipoia, says M\u0101ori have consistently opposed sending human waste to waterways as it is culturally abhorrent \u2013 treated and especially untreated. \u201cFrom a te ao M\u0101ori perspective, it\u2019s unacceptable. We don\u2019t want to eat our poo. I\u2019m sure that\u2019s a view many New Zealanders share. Just notifying people more often and being more transparent about how much poo goes into our water does not lessen the poo.\u201d<\/p>\n

\"Tauranga\u2019sTauranga\u2019s Te Maunga treatment plant pipes treated waste to 950m off a surf beach. Photo \/ Tauranga City Council<\/p>\n

Porou says many M\u0101ori communities prefer treated wastewater to go through Papat\u016b\u0101nuku [land], but shifting discharge from water to land requires pricey new infrastructure. (Just under half of wastewater discharge consents are for discharge to land.) The only window for iwi and hap\u016b to improve things is when treatment plants come up for consent renewal, she says. \u201cYou have to wait for 35 years to get to that point, and so many of our people have been waiting. This is our chance. But now, those windows will be closed because the changes to the policy and the laws enable less engagement and lower thresholds, and that means our ability to defend those waterways is reduced.\u201d<\/p>\n

Porou says iwi and hap\u016b are often the only voices speaking up during consent discussions. \u201cIn larger cities, you just flush the toilet. You don\u2019t really think about it. But for many M\u0101ori communities, they see it going directly into the waterways where they gather kai, they see it going into areas that are important traditional sites.\u201d Some sewage plants are built on w\u0101hi tapu sites.<\/p>\n

M\u0101ori also want to be involved in decision-making about biosolids\u2019 fate. Biosolids are the processed solids that remain when wastewater is discharged, and the new standards include rules for putting them on land. Biosolids disposal costs councils about $40 million annually. A third go to landfills. Several centres near the central North Island send biosolids for vermicomposting, where they are mixed with organic waste and broken down by worms. The vermicast is sold mostly to orchardists, green infrastructure projects and councils. New Plymouth sells biosolids as fertiliser granules. Christchurch fills up holes left by the Stockton coal mine. Some, such as Nelson, spread them on forestry land.<\/p>\n

In the country\u2019s biggest and fastest-growing city, M\u0101ngere\u2019s wastewater treatment plant creates 400 tonnes of solids daily that are filling an old quarry on Puketutu Island in the Manukau Harbour. By 2035, it will be full. The long-term solution will be either a new landfill or a dedicated incinerator, says Watercare\u2019s biosolids planning manager Rob Tinholt. Landfills are hard to find acceptable sites for, and tipping fees are high. For an incinerator site, he says, \u201cwe\u2019re looking north of Taup\u014d and south of Kerikeri\u201d.<\/p>\n

Chemical contaminants<\/p>\n

Biosolids aren\u2019t just poo and pathogens. They also contain abundant soil-fertilising nutrients \u2013 plus residues of many drugs and medicines, personal care and cleaning chemicals, pesticides, microplastics and persistent organic pollutants such as flame retardants and PFAS, the carcinogenic \u201cforever chemicals\u201d. These come from households, hospitals and industry, and current treatment processes don\u2019t remove them.<\/p>\n

\"TreatedTreated wastewater piped into freshwater rivers and the sea still contains nitrogen and phosphorus. Photo \/ Wastewater Services Limited<\/p>\n

But Tinholt says these contaminants are measured in Auckland\u2019s biosolids only at parts-per-trillion (ppt) levels. \u201c[One part] is about a sugar crystal in an Olympic-sized swimming pool.\u201d (PFAS are found at about 4000-11,000ppt in biosolids.)<\/p>\n

He wants more biosolids on land. \u201cIf we want good soil nutrition, how do we achieve that? The good thing about biosolids and compost is they really help with building the carbon content of soil as well. We\u2019ve lost 50% of carbon in New Zealand\u2019s soils. I use biosolids in my own vege garden.\u201d <\/p>\n

About 20% of biosolids already get put on land. What could possibly go wrong? Overseas, biosolids are widely used on food-producing land, lessening the need for synthetic fertilisers, but this has badly contaminated some agricultural land, groundwater and milk with PFAS. The patchy water testing that\u2019s been done here shows comparatively low levels. <\/p>\n

The new standards set upper levels for PFAS and heavy metals only, and pests and pathogens must be reduced. They are seven pages long, but other parts of the world have far more comprehensive guidelines, says David Romilly. He chairs a Water New Zealand group that published 143 pages of biosolids reuse guidelines last year drawing on international frameworks, and he thinks the standards need extra wording to make them clearer.<\/p>\n

The new standards don\u2019t limit or mention microplastics. But they are in biosolids, vermicompost and compost, according to a University of Canterbury study, and they can accumulate in soil.<\/p>\n

Nobody can yet correlate microplastics numbers with effect, says Tinholt, so there\u2019s no agreed limit. They enter agricultural soil anyway. \u201cAll these emerging contaminants, certainly PFAS and microplastics, can be present in all the agricultural chemicals, and that includes seed coatings, pesticides and fertiliser.\u201d <\/p>\n

\"AA Bioforcetech pyrolysis unit supplied by\u00a0Filtec. Photo \/ Supplied<\/p>\n

Olga Pantos, science leader at PHF Science, the Institute for Public Health and Forensic Science, thinks we can do better. \u201cJust because we\u2019re exposed to it in other places doesn\u2019t mean we shouldn\u2019t try to stop it in places [where] we can stop it,\u201d she says. \u201cThe plastics in seed coatings and fertilisers should be stopped. But microplastics are making it into food production land through vermicompost.\u201d <\/p>\n

She points out the UN Food and Agriculture Organisation concludes that even at low levels, \u201cplastic pollution in soils is likely to change the physical, chemical and microbiological properties of the soil\u201d and \u201cis unlikely to be fully reversible\u201d.<\/p>\n

\u201cWe do need to care, and Europe is caring,\u201d says Pantos. The European Union is requiring wastewater and sewage sludge to be monitored for microplastics and other contaminants from next year, and is spending millions to discover how the tiny plastics affect human and environmental health. The monitoring is preparation for placing limits on microplastics and other emerging contaminants. <\/p>\n

Solid alternative<\/p>\n

An increasingly common fix in Europe and in the US is turning biosolids into biochar, destroying most contaminants in the process, apart from heavy metals. It involves heating dried biosolids to around 600\u00b0C in an oxygen-free pyrolysis process that uses little external energy and sequesters about half the biosolids\u2019 carbon content. It\u2019s not happening here yet, but the Dunedin City Council has entered into a staged contract with pyrolysis plant provider Filtec.<\/p>\n

\"OlgaOlga Pantos of PHF Science and Filtec\u2019s Sam Parkin. Photos \/ Supplied<\/p>\n

Dunedin currently incinerates and landfills its biosolids but says that\u2019s becoming increasingly difficult to sustain. Filtec\u2019s compact units firstly dry the solids using heat generated by the sludge\u2019s microbes and the pyrolysis process. After turning them into biochar, Filtec takes it for free or even profit-shares with the council \u2013 a serious advantage for councils currently paying haulage and tip fees.<\/p>\n

Biochar is traditionally used to improve food-growing soils, but Dunedin\u2019s mana whenua have concerns about that, says Filtec\u2019s new business projects manager Sam Parkin, so construction aggregate is the likely first use, and strength-test results look good. \u201cThe concrete guys got excited about using biochar to reduce the carbon footprint of their concrete. Then the question became, \u2018How can we get our hands on it?\u2019\u201d He says higher-value uses are also possible, such as for carbon black pigment (used in rubber products and ink), which is usually made from fossil fuels.<\/p>\n

Not everyone agrees with turning biosolids into biochar. Maria Gutierrez Gines, an environmental scientist at the University of Canterbury, sees it as a waste of resources. She agrees pyrolysis can get rid of some of the trickiest contaminants, but concurs with Tinholt that based on the scanty data available, these seem to be at low levels. Even if biochar is put on food-growing land, \u201cyou lose the nitrogen, and the phosphorus might be locked up. The carbon won\u2019t be accessible for plants or microorganisms.\u201d<\/p>\n

And that is the story of sewage: trade-offs at every turn, whether it be nutrients vs contaminants or money vs water quality. In the modern world, it\u2019s hard to have our comforts and to also affordably keep our nest clean. <\/p>\n

Flush toilets are considered by some as one of humanity\u2019s most unsustainable innovations. About 20% of drinking water that\u2019s piped into households is used to flush toilets, becoming filthy with urine, faeces and other contaminants, and it\u2019s expensively made semi-clean again before being discharged to the environment.<\/p>\n

Another option is waterless or composting toilets. They can be buckets under toilet seats or conventional enamel thrones specially designed for the job. Unlike flushing, they require users to responsibly deal with their own waste.<\/p>\n

One features in Whang\u0101rei\u2019s Hundertwasser Art Centre because artist, architect and environmentalist Friedensreich Hundertwasser was a proponent of humus toilets. \u201cHe perfected it,\u201d says his old friend, artist Thomas Lauterbach, who uses one. \u201cThere\u2019s no problem with odour, I can assure you.\u201d<\/p>\n

There\u2019s a toilet seat atop a large bucket. Users cover each deposit with soil humus, which is probably rich in decay-causing bacteria. After three months of storage, the contents have decomposed, says Lautenbach. He reuses them firstly as the toilet\u2019s humus layers and eventually under fruit trees. The composting toilet building code requires storing compost for a year and burying it shallowly. Toilets may need building consent.<\/p>\n

\"\u201cThere\u2019s\u201cThere\u2019s no odour\u201d \u2013 Thomas Lauterbach and his humus toilet. Photo \/ Supplied<\/p>\n

Planning where to put mature \u201chumanure\u201d is important, says Dylan Timney, of Waterless Composting Toilets NZ, which sells a variety of non-flushing toilets. He says aged solids are excellent soil conditioners but not suitable for edible gardens. Timney advises on products according to people\u2019s living circumstances and property type. \u201cYour section is your solution,\u201d he says, and there\u2019s no cookie-cutter answer. \u201cWe\u2019re very stern about advising customers about what and how, and what they can do realistically.\u201d<\/p>\n

His toilets cost a few thousand dollars. But septic tanks aren\u2019t cheap, either, and he says some composting toilets last a lifetime whereas septics eventually need replacing. <\/p>\n

Poorly maintained or older septic tanks pollute water, but all discharge some contaminants even when well maintained, says Chris Ingle, of the Bay of Plenty Regional Council. They were contaminating Lake Tarawera with faecal bacteria and nitrogen, so last year, a reticulated sewage system was built to replace them.<\/p>\n

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