Wastewater

Wastewater comes from various sources in our homes and businesses such as the bathroom, kitchen and laundry, but it doesn't just disappear when you pull the plug or flush the toilet! It goes through a crucial journey.

In the Rangitīkei district, we collect around 1.4 billion litres of wastewater from approx. 4,500 homes each year. Once it goes down the drain, your wastewater gets transported through a network of pipes to one of our seven wastewater treatment plants across the district. Our wastewater treatment plants are located in Marton, Taihape, Bulls, Koitiata, Mangaweka, Hunterville, and Rātana and ​​are maintained with support from the Manawatū District Council.

Once it arrives at the treatment plants, it goes through a cleaning process where we reduce harmful bacteria, fungi, parasites and viruses. This cleaning process aims to minimise our environmental impact before we eventually release the treated wastewater back into our waterways or on land.

Discharging into our waterways
In the Rangitīkei district, we discharge most of our treated wastewater to our streams, rivers and oceans. Although the wastewater has been through a cleaning process, it cannot always remove all the impurities, which can affect the quality of our waterways.

Discharging treated wastewater into larger water bodies, like the Rangitīkei River, may not affect the environment as much as a discharge to smaller streams due to their greater water flow, which helps to dilute the treated wastewater and disperse any remaining germs and pollutants.

Discharging treated wastewater into lower flow streams, on the other hand, will have a more significant impact. For example, Marton’s wastewater is discharged into the Tūtaenui Stream. During the summer, the stream completely dries up, and the only water source of the stream comes from the wastewater treatment plant. Unfortunately, this has led to an increase in nitrogen, phosphorus and other harmful substances in the streambed. These substances can cause excessive algae growth, which lowers oxygen levels and harms fish and other creatures. As a result, the stream has become unusable for our community.

To address this issue, one of our top priorities is to stop the discharge to the Tūtaenui stream and instead find a solution combining the Marton and Bulls wastewater and discharging this on land or to much bigger, steadily flowing waterways such as the Rangitīkei River or the ocean.

Discharging to land
We also discharge some treated wastewater to land. Once well-treated wastewater is released to land, any remaining nutrients that are left in the wastewater will be taken up by the soil, plants or trees. The plants grow taking the nutrients from the treated wastewater and turning carbon dioxide into oxygen – a double win for the environment.

Wastewater needs to be treated to a level where it has very minimal effects on the environment it is discharged into. If wastewater isn't treated properly before being discharged to land, the nutrients may go through the ground into groundwater, wash away into our waterways or affect the quality of plants and soil.

Normally the land that wastewater is discharged to only gets used for the harvesting of trees or fodder for animals, it is not common practice in New Zealand to use treated human wastewater on food crops for humans or for grazing dairy cows.

There are several ways we can contribute to the wastewater process and help minimise its impact on our environment:

1. Use less water
   Every drop of water we save directly impacts the health of our waterways, aquatic life, and the overall wellbeing of our planet. When we use less water in our homes and businesses, we can reduce the volume of wastewater that needs to be treated. This means less energy and resources are needed for wastewater treatment, which means we can reduce our environmental footprint. With less wastewater going into our waterways, we can help make sure that they are safe and sustainable for future generations.
   
   Want to do your part to conserve water? Try things like taking a shorter shower, turning the tap off while you brush your teeth, or only turning on the washing machine when it’s full. For more ideas, visit Water for Life.
   
   
2. Dispose of harmful substances properly
   Even though wastewater gets cleaned at our treatment plants, what we pour down our drains still matters. Our wastewater treatment plants do their best, but they can't remove everything. Many common cleaning products, soaps, medicines, paint and other harmful substances contain tough-to-handle chemicals that can affect the quality of our waterways and the aquatic life that lives there.
   
   
3. Choose environmentally-friendly products
   If you can, it’s important to use cleaning products, soaps, and detergents that are made with natural ingredients. Eco-friendly products are less toxic to aquatic life and break down more easily. By opting for these products, this means you can help make the wastewater cleaning process smoother, ultimately reducing your impact on the environment.
   
   
4. Dispose of waste properly
   It’s important that we put things in the right places! Make sure you throw food scraps, oils, and non-biodegradable items in the bin or compost instead of the sink or toilet to prevent blockages.
   
   Food waste can actually cause clogs and stop wastewater from flowing properly if too much of this waste builds up in our pipes over time.
   
   Did you know that the food waste you put down the insinkerator ends up in landfill anyway? When it arrives at the wastewater treatment plant, it gets separated from the wastewater and disposed of, along with other solid bits. If you want to reduce your environmental impact in your kitchen, we encourage you to collect your food scraps and compost at home.