Composting Toilets

A natural solution to reducing water use

One of the benefits of modern homes is that families can use the toilet without having to think about where their waste goes. However, every time we flush, wastewater begins a long journey back into the environment.

First, it is typically pumped from our homes through networks of pipes to central treatment plants. It is then treated, often to drinking-quality standard, before being released back to our waterways or sprayed onto the ground. Every year, in every home, thousands of litres of water are used as a transport medium to flush toilets. Flushing accounts for 18% of the total water usage in New Zealand households(1) and in a hospitality facility like Camp Glenorchy, the amount of water used for this purpose each year could easily be more than 300,000 litres(2)– enough to fill the sizable Amenities Building on site.

However, at Camp Glenorchy, we’re aiming to reduce that 300,000 litres to zero, partly by using flushless composting toilets in all new buildings on the site. These simple yet state-of-the-art toilets will help us achieve our goal of using 50% less water than similar facilities, and providing for our own water needs as much as possible.

As well as eliminating the need for flushing in these buildings, we will generate virtually no wastewater. This reduces the need for wastewater treatment and minimises any effect on groundwater sources. Choosing composting toilets means we’re taking on responsibility for treating our own waste, but it comes with its rewards too! Treated compost generated by the toilets will serve as nutrient-rich food for the native plants on site.

How do they work?

DecomposingCOMPOSTING TOILET

Composting toilets require no water for flushing. When you use the toilet, your waste drops down a pipe into a tank where natural processes break it down, transforming it into a soil-like material called humus that can be used as fertiliser for your garden. In fact, the Phoenix Composting Toilets at Camp Glenorchy work much like garden compost piles, using food, air, bacteria, moisture and heat to transform waste into a usable end product that doesn’t contaminate the environment and isn’t harmful to humans.

Maintenance

Maintenance is a key requirement for composting toilets to work safely and efficiently. Depending on how frequently they’re used, owners need to perform weekly, monthly and yearly tasks. Frequent tasks include adding bulking agents (such as white wood shavings) to make waste more porous and, in the case of the Phoenix Toilets we're using, rotating a crank handle located on the tank to help with the downward movement of the pile. The moisture level of the waste and the cleanliness of the components also need to be checked every few weeks. On average, finished compost is removed once a year from the bottom of the tank and turned with the soil in the garden as fertiliser. 

When they are well-maintained, composting toilets do not have any odd smells. Like a standard toilet, if they smell at all it generally means something is not working as it should and needs to be fixed.

Composting toilets at Camp Glenorchy

To achieve our water goals, we will be collecting rainwater, using efficient fittings and reusing greywater, in addition to the composting toilets. There will be 21 toilets installed on site, with six in the Amenities Building, one in the Maintenance Building and two in each cabin. We estimate the 21 toilets will generate approximately 2.4 m³(3) of compost each year. 

Each building that has a composting toilet installed will have a cellar or basement where the tanks are kept at a stable temperature year-round. Tours of the Amenities building basement will allow visitors to learn first-hand about the Phoenix composting toilets and the way they work. 

When guests open the toilet lid, air from the room will be pulled down the toilet into the tank and then expelled through a vent on the roof. This means each time one of our composting toilets are used, the bathroom will actually smell better than before!

When using a toilet in one of our cabins, guests ‘flush’ it by throwing a handful of wood shavings down the pipe, which helps with processing the waste. Toilets in the Amenities building are a little bit different: guests there won’t need to do anything. Maintenance staff will add wood shavings directly to each toilet's tank, as frequently as once a week during peak season. 

How could composting toilets affect our larger communities? 

Modern cities rely on a vast network of water infrastructure to deliver potable water to buildings and collect wastewater for treatment. Costs of operation, maintenance and upgrades to keep up with increasing demand are high. How high? Ratepayers across the Queenstown Lakes District will need to pay an estimated $27,000 a day, every day for ten years, for new infrastructure works required to meet the growing peak demand(4). 

Using a composting toilet instead can dramatically reduce demands on water infrastructure by eliminating the need for almost tens of thousands of litres of water every year for flushing(5). This preserves both money and resources. In Auckland, for example, each cubic metre of wastewater treatment costs 59% more than a cubic metre of drinking water(6) due to the complex process it undergoes to make it safe. 

In New Zealand, composting toilets currently can’t be used in urban areas where a mains sewer connection is available. However, authorities can provide a waiver and some Councils have been very receptive to the idea. 

Composting toilets can be especially beneficial to communities without a public sewer infrastructure by reducing the amount of waste sent to septic tanks and of leachate to dispersal fields, helping protect underground aquifers. In Glenorchy, Camp Glenorchy's home, this issue has been identified as a potential risk due to the shallow groundwater level. Increasing levels of discharge from a growing resident and visitor population may eventually impact the bore that is used for town-wide potable water supply. Technologies such as composting toilets could reduce the required investment in sewage treatment facilities as well as the size and frequency of upgrades by reducing the amount of water that needs to be treated. 

Our commitment

At Camp Glenorchy, we are committed to living in harmony with nature and reducing our impact on the environment. The use of composting toilets reduces the impact on Glenorchy’s groundwater reserves as there will be no wastewater from toilets and the small amount of leachate produced will be treated on site.

We’re aware that composting toilets will require more care and maintenance than conventional toilets, but instead of flushing the ‘problem’ down the toilet, we we've made the choice to take responsibility for our waste by transforming it into a valuable end product that will be used on the site.

Camp Glenorchy's composting toilets be rigorously maintained on a strict schedule, ensuring our guests have a comfortable and enjoyable stay. Doing so will ensure there won’t be any odors, and the end product will be inoffensive, dry and safe for everyone.

Testimonials Sustainability Campground
Testimonials Sustainability Campground
Testimonials Sustainability

 

What can I do at home?

Composting toilets are a viable alternative to on-site wastewater treatment in areas where connection to a public sewerage system is not available or where water is scarce. If you are thinking of installing one consider the following:

 

  • Check with your local council

    Find out if you are allowed to build one and what regulations and requirements you need to comply with. Some councils will be more accepting of the idea than others.

  • Weigh the environmental and economic costs of your decision.

    For example, if you are in a remote area and using a holding tank, sucker trucks could be expensive. A composting toilet is likely to reduce the frequency of collection as well as the use of drinking or rainwater.

  • Find a system that works for your family and lifestyle.

    Even though most composting toilets work under the same principle, operation differs from one system to another. There are two main types of composting toilets:

    1) Continuous composting toilets that, like the Phoenix, have a tank underneath that is constantly receiving new waste while producing compost at the same time.

    2) Batch composting toilets need more than one container. When full, the tank is removed and set aside to decompose, while an empty container takes its place.

  • Check you have the space required.

    If you’re retrofitting one into an existing home, check you have the space required to fit the system you have selected. If you’re building a new house, manufacturing companies will be able to help you with the design to ensure the system fits and works in the best possible way. For example, the Phoenix requires room underneath the house to accommodate the tank and dry toilets need to be installed directly on top. You’ll also need to fit two pipes: a vent pipe from the tank to the roof and a drain pipe from the tank to a holding pump or gravity sewer for disposing of excess liquid.

  • Maintenance and commitment.

    Remember that composting toilets will require more maintenance and commitment than normal flushing toilets. However, your effort will be rewarded with rich compost that will become food for plants. Careful maintenance will ensure the end product is of the highest quality, healthy for humans and free of smells.



 

Footnote:

1.BRANZ, Water End Use and Efficiency Project (WEEP), pg. 22
2. We have estimated annual guest nights at Camp Glenorchy to be around 26,000. If using flushing toilets, a common assumption is that each guest would flush two half-flushes and one full flush every day, or 11.5 liters per person per day.
3. In optimal conditions, the Phoenix Composting Toilet will produce 30 liters of compost for every thousand uses. Based on the number of flushes per vision above, we estimate Camp Glenorchy will generate about 2,400 liters or 2.4 cubic meters of compost per year.
4. Queenstown Lakes District Council, Conserving Water.
5. Average of 12.9 flushes per day per household and an average flush volume of 6.2L (based on BRANZ study) = (12.9*6.2)*365.
6. Based on Watercare prices effective in June 2016, a cubic meter of drinking water costs $1.409, while the same volume of wastewater is charged at $2.394.

  

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