Living rural and off-grid: how to choose the right onsite wastewater system for your property

How often do you think about wastewater management? Chances are, never. This necessary but rather unglamorous system chugs along in the background for most — so, if you’re designing an off-the-grid home for the first time, you’d be forgiven for feeling out of your depth at the prospect of choosing an onsite wastewater system. 

As off-the-grid properties do not have access to council sewer mains, they need a system that can treat and dispose of their wastewater onsite. This process consists of the treatment of raw wastewater through a treatment and land application system where treated effluent is returned to the environment through the soil.

“An onsite wastewater system is a biological process that uses bacteria and other microbes to treat the sewage, removing any toxic material so it is safe to return to the environment,” explains Salma Rayan of wastewater specialists, Innoflow.

Because the treated effluent ends up in the soil, it is crucial to choose a robust, reliable, and proven wastewater system to ensure the effluent doesn’t cause any personal or environmental issues.

Key considerations for onsite wastewater systems

Before selecting a system, you will need to engage an onsite wastewater system designer to do a site assessment. 

“These assessments consider the planned development, the land’s capacity for receiving treated effluent, the sensitivity of the receiving environment, and the regional regulatory requirements for an onsite wastewater system. Once you have a wastewater report outlining the minimum requirements, you can then do some research or engage a relevant supplier to find a suitable system,” Rayan explains.

“For off-grid properties, an onsite wastewater system should best service the property’s usage and receiving environment. Like anything in construction, there are several factors to consider when selecting a system for your property.”

These factors include the size of the house and the number of people it is designed for; the size of available land for treated effluent disposal and volume the soil can receive; the sensitivity of the surrounding environment; power availability; frequency of system use; site constraints; and the site owner’s commitment to appropriate use. 

With the range of systems available on the market, it can be difficult to know which is best suited to your property. Most people will only buy an onsite wastewater system once in their lives; with such a significant investment, sustainability is key. 

“Failure of your onsite wastewater system is detrimental to you as the site owner, and disastrous to the receiving environment,” Rayan says. 

For this reason, it’s crucial to choose a system designed to last the course of a typical site lifetime, which is about 50 - 70 years. 

To ensure the system you choose will meet the requirements for your property, Rayan recommends asking the following questions: 

• How well does the system cope with intermittent and shock flows? 
• What is the power consumption and expected sludge pump out frequency? 
• How often does the system need to be serviced? 
• How often will the pumps and parts need to be replaced, and what warranties are provided? 
• What is the system’s track record, and does it have relevant performance certifications?

AdvanTex secondary treatment systems

Designed for all off-grid sites, AdvanTex systems provide higher treatment than primary treatment systems (septic tanks and trenches), with lower running costs, sludge production, and servicing requirements than most other off-the-shelf aeration plants commonly available. While the up-front costs are higher than other systems, the benefit of a system suitable for variable flows and solar-powered sites, and the long-term savings on running costs, is worth the investment. 

Due to their ability to cope with the specific demands of off-grid sites, AdvanTex systems have been installed on thousands of properties across the country. With low power consumption and solar-power compatibility, the systems are ideal for residential sites. And, as one of the few systems that can cope with fluctuating loads, they offer peace of mind for homeowners hosting large gatherings. 

Installation of AdvanTex systems is relatively simple, even on sloping or remote sites, due to its lightweight structure, durability, and packaging.

“The AdvanTex systems are also scalable. The system consists of pods, and some tankage, with each pod allowing for 2,000 to 1,000,000 litres per day in capacity. These can be added to a new system as required, or retrofitted to existing tanks or systems if you’re renovating,” Rayan explains.

“Innoflow is the sole supplier for AdvanTex onsite wastewater systems, and we have been exclusively supplying and installing them across New Zealand for close to 30 years. With this breadth of experience, we can guide homeowners, architects, and design professionals towards a solution that will work best. Plus, as these systems are well-known by councils around the country, it’s really easy to get consent.”

Learn more about Innoflow.