Septic Tanks

Failing Septic Tank?

Our team of professionals can assess your system and suggest remedial action.

Wastewater treatment systems are our passion. And finding the right treatment system for your wastewater or sewage is what we do best.

The history of the septic tank dates back to the mid-19th century and is rooted in the evolution of sanitation practices aimed at improving public health. The invention of the septic tank is often credited to Frenchman John Mouras, who in 1860 developed a prototype system at his home in the village of Vesoul. Mouras, along with a local scientist, patented the design in 1881.

Septic Tanks provide a level of independence and resilience, relying on simple passive technology that effectively treats wastewater through natural anaerobic bacterial processes and hydraulic retention and stratification, which is a slow passive process of separating the solids from the liquid.

However Septic Tanks on their own aren’t commonly used in this age, due to both a lack of treatment and environmental concerns of the industry and regulators. Instead, there is a push towards more advanced treatment systems.

That doesn’t mean they are disappearing anytime soon. There are still a handful of applications where a conventional septic tank is permitted and may be suitable, such as large properties with free draining soils and no water bodies nearby.

We do install septic tanks, but before you look at this option for your site there are two things to consider: price and the environmental impact.

How Do Septic Tanks Compare? It’s often thought that septic tanks are the cheaper way to go, compared to treatment systems. Not necessarily.

In our experience, septic tanks offer little price benefit when it comes to installation. They are predominantly concrete so require good access and a Hiab to position them. Plastic tanks are available for more difficult sites, but they do traditionally come at a higher price, depending on size.

The overriding consideration if using a septic tank is size both in tank sizing and disposal field sizing. Size is the biggest contributing factor to minimising any risk of environmental harm and a ‘smelly’ backyard, due to the minimal treatment a Septic Tank provides.

If your site is suitable; Waterflow has many options available and will step you through all the necessary calculations, to ensure you choose a size that is truly fit for purpose and sustainable.

Due to the distinct ‘septic’ odour and low levels of treatment a much more robust land application system must be considered. Effluent should be discharged into the ground via a soakage bed system - these require excavation and more material so do increase initial investment.

How Do Septic Tanks Treat Wastewater? The principle of a septic tank is this: the wastewater all enters a tank of one or more chambers, in each chamber the solids settle to the bottom and the scum floats to the top. The clear water in the middle then passes to the next chamber and finally out to a soakage area.

Anaerobic bacteria inside the tank break down solid matter at a very slow rate, therefore the solids accumulate in the bottom of the tank and require periodic removal (suck outs).

The discharged water has no large solid matter but can contain various contaminants; the final and main treatment occurs in the soils where the effluent is discharged. While the settling process and anaerobic organisms provide Primary Treatment, the wastewater is not cleaned nearly as thoroughly as it would be using a vermifiltration or aeration system.

Understanding these strengths and weaknesses can help homeowners make informed decisions about installing and maintaining septic systems, ensuring they function efficiently and safely for the long term.

Common Problems

Many old septic tanks are starting to fail, or no longer meet the current standards.

Blocked Soakage Field Some old septic tanks have no outlet filter, allowing solid material to exit the tanks and enter the land application system. This leads to blockages and results in backed up drains and sewerage overflowing onto your property.

Most old septic systems rely on a trickle discharge, essentially what goes in comes out. Since the land application system is only receiving a small amount of water at a time, it tends to soak away at the beginning of the soakage area; until the constant flow causes a build-up of slime and sludge and blocks the soil, then it progresses along a bit further; this is called ‘creeping failure’. Over a number of years, the entire area will block up.

We can reinstate your land application system to its original state, as long as we know where it is and how big. If the area or location changes significantly, a building consent will be required, otherwise it can be done as repair work. We will dig it up and use new materials to reinstate it.

In many cases, the most future proof option is to bring the land application up to standard and get it approved by council, as this will improve the current operation and future sale value of your property. By doing this we can also add a dosing module to the septic system, improving the loading of the soakage and increasing its life span.

No Septic Access Hatch We can improve access to the tank by adding a riser and lid to an existing septic tank.

To meet current regulations, every septic should have an access maintenance hole. Many old septic tanks had a concrete hatch buried under the ground; which meant that when a suck out was being carried out the hatch would have to be dug up to fully suck out the tank.

Ground Water Backflow Most old septic tanks rely on a trickle discharge, which can cause complications.

If there is high ground water, it can flow back through from the soakage into the septic. This typically occurs on flat sites where the water can’t get away easily. In this situation, large rain events can prevent the septic discharging correctly, in the worst case resulting in sewage overflowing out of the tank onto your property, which is definitely not what you want to happen.

This can be remedied by adding a dose tank to the end of the septic and pumping it into the soakage area. The pump forces the water into the soakage area, where it is unable to return to the tank.

We also have smaller gravity dosing modules to improve the dosing of soakage areas.

Broken Inlet/Outlet Smelly on the Inside and Out

Broken inlet pipes can result in sewage landing on the top of the effluent in the tank. This breaks up the crust, turning your tank into a smelly soup. Simply replacing the inlet junction can stop the smelly problems you are experiencing.

Broken outlet pipes mean there will be no outlet filtration, leading to blockage in the soakage field. Blockage in the soakage results in break out and smelly wet areas on your property.

"We are happy with the installation of our septic system thanks.

The speed from us saying that we were ready for the installation and the job being completed was great. Also the site being left in a nice clean state was exceptional.

Great people all round to deal with. Thank you"

Meghan and Keith - Kaipara October 2020


We’re in 6,000+ backyards around Aotearoa New Zealand

At WaterFlow we work across the country recommending and installing smarter wastewater and sewage systems, for a cleaner New Zealand.

Whether it’s upgrading a water tank or installing a new water system, we always offer bespoke solutions designed to fit your environment and lifestyle. Take a look at our recent projects to be inspired.

Passive Solar Home

Our clients came with the mission of creating their own passive solar home. The NaturalFlow system was an obvious choice, being power-free. We were able to help them achieve their dream on this awesome property.

Off-grid, tiny homes
14 December 2023
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Family Home

The EconoTreat was perfect for this family home. With higher volumes of waste and council requirements of secondary treatment, they needed a system that would provide a consistently high treatment.

14 December 2023
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Packhouse Accomodation

With large seasonal fluctuations, this kiwifruit packing facility needed capacity for peak season staff. A custom designed system by WaterFlow met the requirements for the project, with the capacity to process up to 54,000L per day.

14 December 2023
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Otamatea Marae

Struggling to have enough water to sustain the events, we were asked to upgrade the water tanks and drainage. With an additional four 25000L tanks, they aren’t likely to run out any time soon!

Marae & Light Commercial
14 December 2023
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Rural Oasis

The Naturalflow NF8000 System was used in this piece of paradise. The landscaping gives it a tropical feel, as you step through to the pool for some quality time out.

14 December 2023
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Bahá’í – Henderson

With major upgrades to the building and facilities, the Spiritual Assembly of the Bahai’s was in need of an upgraded wastewater system.

Marae & Light Commercial
01 December 2023
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"Just a note to say that we are totally impressed with the install job done with the septic yesterday. Sid and the builder couldn’t believe how they left the site so tidy."

Sid & Glenda – Mangawhai September 2016

"There is absolutely no smell, the system makes no noise and can easily blend in to the surrounding garden.

I have and will continue to recommend the system to others who are in the market."

Alex Boles – Waikato July 2016

"I am really impressed with your company and will rave about you to all who show interest in eco-sustainable systems."

Genevieve - Mangawhai June 2019

“We feel very fortunate to have had the pleasure of dealing with Ken and the team at Waterflow NZ. Their commitment to their product and services is exceptional, going above and beyond to ensure total client satisfaction, and delivering a quick and tidy job. We found it very easy to communicate throughout the installation and commissioning of the Naturalflow system. We totally recommend their product and their competent service to anyone!”
Julie Borwn, eHaus Waikato

Julie Brown – Hamilton September 2018

“I was looking for a wastewater and sewage system which did not require power to operate and was environmentally friendly and didn’t require regular servicing. Since our system would be down hill from the house and sloping to the proposed field I thought it was a possibility! I found NaturalFlow and researched the system and liked the idea of the Wormorator for treatment of the blackwater. Our installation went smoothly and fitted in with our landscaping nicely. We are very happy with our system and the service from the NaturalFlow staff is second to none! We had a couple of minor problems which were promptly and professionally taken care of. As a builder with 40 years experience it was a pleasure to work with a company with such integrity and back up service."

Michael Kriz – Langs Beach November 2017

“I just talked to your colleague and I will be meeting with him tomorrow on site.
I must tell you that the efficiency you work is fantastic- a breath of fresh air for us 🙂
We were very impressed how long it took for you guys to organise from one day to next for someone to contact us and also the guy who called us was very flexible and we can meet him at a time which works for us.”

M. Foldkozi January 2019

"This system appealed to us the most, due to a number of factors. This was because the basic principle of the system is to recreate what Nature would do in a virgin forest situation....The local camping ground has this same system but has two Wormorator units, and the proprietors comments to me when he was asked about this NaturalFlow system. “Was that it is an absolute no brainer to choose this system as it can take ‘shock loading’ and also handle times of very little use.”
We have also been extremely impressed with the after sales service and back up. If we were to ever develop another property we would go with the eco-friendly, Natural Flow system without giving it a second thought.”"

Stanley Armon June 2022

“Around 2004 we started to have problems with our septic tank system on our Ruawai Flats property. Intial inquiries showed it would cost between $9 – $11K to fix the problem. While we were pondering this, quite by chance I read your advert in the Lifestyler offering an alternative system. After some investigation we decided to go ahead and your company installed the system in just one morning.

There has been no teething problems, there has never been any untoward smells and maintainance and compliance cost’s have been zero. Hence I can recommend this system without reservation.”

A D Radich February 2019

"Thank you, we are pleased with the way that you finished the installation and particularly Jimmy’ s work with cleaning up the site. Please thank him for us.
We enjoyed your company, regards Steven"

Steven – Rakino Island February 2019

"To Whom it may concern.

Waitoki School’s decision to go with Water Flow Nz Ltd, was one of the wisest we have made.

The quality of both product and service is exceptional. 

Their care of ‘post installed product’ is timely and professional.

One of the trickier elements when installing in a school environment, is the installers ability to run a safe secure installation – and Water Flow stood out with their professional approach to working around children.

Chris Neison – Principal"

Waitoki School – Waitoki February 2020

"Was actually fun working with the guys.
They did all the work naturally…

Couple of Ciders at the end of the day, great company. 

Many thanks again."

Maaike – Kawau Island November 2020

“Back in 2008 along with our building projects we decided to go for the NaturalFlow sewage system as it didn’t require any power, on our site. We have been very impressed with the performance of this system, with very little maintenance, it basically looks after itself.

Without hesitation I would recommend the NaturalFlow system to anyone as I have had no difficulties with product or the friendly team at WaterFlow NZ Ltd."

M. Vincent February 2023

"Building on a section with Harbour views which we love and also need to protect - having a septic system that is very environmentally friendly was a must. We had lots of good reviews on NaturalFlow so choice was made easily.

They were great with communication, service and all staff very respectful and professional.

I am using ecostore and earthwise products for everything as we also need to take care of the worms 😊

Have already recommended them to others who are in the process of starting to build soon.

👍 highly recommended 👌"

Thea - Paparoa March 2022

"Easy system to look after and operate. We are very pleased with it and are glad we went with the system. The grey water has certainly been great on the gardens and the black water bed once planted looks after itself. Great!"

Dennis & Marie February 2023

"Everyone in your team from your sales, design and the delivery guy has been so knowledgeable and fantastic to deal with.

Everyone that has been here for site visits and install have been so easy and a pleasure to deal with. So much so we are choosing you guys to do it all over again with."

Jo - Kaukapakapa February 2023

"Kia ora, I've been dealing with many different aspects of getting a small house built for us on our section for the last couple of years, and it's taken a long time because so many people we have engaged have been slow or unprofessional in their work.

The two people who really stand out as complete contrast to this work for you - both Caleb and Sandra have been nothing but absolute treasures in this process. They have been professional, knowledgeable, helpful, and extremely patient. We could not be happier with their work.

Thank you for employing such excellent staff."

Joey - Waitakere January 2023

"A big thank you for Adam’s efforts today. He braved the rain and very efficiently checked the system, repaired the two leaks and also helped us out with some paper work. You have a good set up.

Thanks again and best wishes to you and the team there."

Tony - Waipapa November 2022

"I have found your entire staff a pleasure to deal with.

Your first contact personnel, sales people, sales support and installation team have been very helpful and courteous; nothing has been a problem they can’t fix."

Frank - Riverhead June 2022

"Thanks for getting Adam out so quickly today.

FYI, he was extremely helpful in explaining the system etc and I really appreciated his approach and advice."

Paul - Waipapa June 2022

"Yesterday while your workers were at 90 Opito Bay Rd the elderly gentleman owner had a fall grazing his knee and appeared to be a little confused. Some how, someone went to the extra caring mile to find a contact to alert his accident to family.

I want to acknowledge this wonderful & heartwarming humanity with a big thank you. Above and beyond great service!"

Chris - Kerikeri May 2022

"Waterflow n.z. supplied and installed the wastewater system on our lifestyle block completing it on the last working day before the Christmas holidays.

We love the system and were very satisfied with the installation and service. They were great to deal with and left us feeling confident in future servicing and maintenance."

Peter - Whananaki March 2022

"We've been really impressed with the service and professionalism from your team - thank you.

Gary also did an excellent job, very tidy, great to communicate with, and happy to accommodate our requests."

Lauren - Waimauku February 2022

"The biggest thanks to you and your team. You have all been an absolute pleasure to work with and would highly recommend at any time to everyone. Thank you all.

We are so stoked with the outcome and can’t wait for the system to get up and running. A massive thanks to Gerald too for taking the time to educate me in all the ins and outs of sewage – all of you were all so helpful and made the process sooo easy."

Rebekah - Kaipara Flats December 2021

"Water Flow has been an absolute pleasure to work with from start to finish.

Everyone has been knowledgeable, friendly and professional. Your contractors are excellent, highly skilled and very professional. Communication has been exceptional

I have no hesitation in using your services for our new house system and would highly recommend your services in the future."

Andrew Chapman - Hakaru September 2021

"Gavin was great during the installation and so far all has gone well so thanks.

The site has been left well-groomed and with minimal mess, which considering the time of year and amount of water around is very much appreciated."

Aaron - Kaiwaka August 2021

"Thank you for making it such a smooth process with excellent communication and even better customer service.

You arrived on time, completed the work to a high standard and caused no issues for us. Thank you must go to you all."

Otamatea Marae April 2021

"We are happy with the installation of our septic system thanks.

The speed from us saying that we were ready for the installation and the job being completed was great. Also the site being left in a nice clean state was exceptional.

Great people all round to deal with. Thank you"

Meghan and Keith - Kaipara October 2020

"Thank you for your services, you have an excellent working crew and you all in the offices there made the whole paperwork and organizing of the job processes so easy for me it was so good to leave it in your hands and not be doing it myself, as I had to with the rest of the stuff I’ve had to do during this time."

Thelma - Ruawai June 2020

"To Whom it May Concern Our Papakainga in Pouto (currently 8 homes on site) had major septic issues and due to Health & Safety reasons the Council was justified in demanding an upgrade.

Natural flow provided an environmentally sustainable system that uses a natural process to treat our wastewater to a very high standard. This was extremely important to us as the Papakainga lies adjacent to the Kaipara Harbour.

To date we have experienced great service and maintenance of the system and the Council is happy too."

Pouto Papakainga – Pouto March 2020

"Thank you very much for the work & installation of your system.

It was a pleasure to see how fast, efficient and what an excellent job they have done, nice and tidy job too, very impressive thanks again, I will enjoy using this system knowing that it's environmentally friendly too."

Victoria - Tinopai July 2020

"Just wanted to add that you guy's have been amazing throughout this process, Gerry has been so great to deal with, himself and the other two guys were super efficient and very tidy completing the job on site and it was done on time even with my dates getting pushed out and not 100% confirmed until about a week out from the house arriving on site it felt like it was no issue to Gerry and he was very accommodating.'

Emily - Hatuma November 2019

"I have to say i am very impressed by your work done given what was the potential. I agree i think its fairly late in the season to worry too much about Grass recovery and if it does need a bt of a help it won’t be until closer to spring anyway, but for now its looking good.

Thanks again. We can touch base later around that. Thanks again, were really impressed by your Company.

I would have absolutely no hesitation in recommending anyone in both the product and your after care support. We really appreciate it!"

Mark - Te Kauwhata June 2019

"I would also like to thank you guys for your exceptional customer service. we have been impressed by the professional attitude by your team.'

Glenn - Ruawai June 2019

"I just wanted to say ‘thank you’ for sending two such lovely, competent men (Hamish & Rangi) to repair our septic waste water field.

They were 100% professional and a real credit to Natural Flow."

Leesa - Whangteau May 2019

"We have been super happy with our new Wormerator. The guys were absolutely awesome on the installation. Jimmy, Terry and Rick were so hardworking, thoughtful and friendly.

They have done an outstanding job. Mary Kay was also very helpful in all our communication."

Jessica - Ngunguru January 2019

"Just a quick note to thank you guys for doing such a great job for us. You made the process very clear from the outset and kept us totally informed along the way.

The drain layers turned up when they said they would, worked in appalling conditions and came back to finish off without a grumble. I wish all our dealings had been so trouble free.

Thanks again to you, Ken, Garry and Terry the drain layers and your team."

Warren - Kumeu September 2018

"Stoked with the work done, the boys on the diggers did an awesome job. Everything was left nice & tidy, super happy!!"

Cullen - Stillwater November 2017


Protecting the Future of Your Property and our Shared Backyard
At WaterFlow we are with you from start to finish – and beyond. Once installation has finished, we are still on hand to provide, maintenance, support and servicing.

Discover ways to maintain your systems in between servicing and how to contact our expert service technicians.


All you need from first inspection to post-install support

For trade professionals, working with WaterFlow means gaining a reliable lifelong partner committed to achieving project success, and a team that values collaboration, precision, and timely execution.

It all starts with your site

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Not sure what will work for you? Let us take a look.

Your site and dispersal field have the biggest say in which system will work best for you. Let our team take a look, either on site or via aerial mapping, and we can help you find a solution that works for you.

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