Wastewater

Wastewater comes from many sources, such as:

• households — poos, wee, laundry water, toilet paper, rubbish, medicines and cleaning products
• industrial production — toxic chemicals, heavy metals, persistent organic pollutants and oils
• agriculture — irrigation run-off, animal waste, agricultural chemicals and medicines
• urban environments — stormwater, rubbish, vehicle pollution, public toilets and other debris.

Wastewater contains pathogens such as bacteria, viruses and protozoa (a group of single-cell organisms). These can cause disease if people come into contact with them. The most common symptoms caused by contact from wastewater are:

• stomach bugs
• throwing up (vomiting)
• runny poos (diarrhoea)
• skin, throat, ear and eye infections
• chest infections.

Wastewater can also contain chemical waste. If it enters our waterways and coastal areas people, animals and plants can be exposed.

Systems in New Zealand to keep people and wastewater separate are normally very effective. However, there are situations where people can come into contact with wastewater. This most often happens when wastewater overflows out of a sewer or wastewater pipe, usually because the pipes are blocked or overloaded during heavy rain.

In areas without piped sewage systems, some form of onsite wastewater disposal is used. Septic tanks are the best-known variety and are common in rural parts of Aotearoa.

Wastewater overflows can contaminate streams, rivers, harbours, and the coast. This can make swimming and collecting food from these sources risky.

We can all play a part in helping prevent blockages, by:

• only flushing, poo, wee and toilet paper down the toilet
• throwing fats and oils from the kitchen into the waste bin once it has gone hard (solidified), instead of washing down the sink.

The role of public health

Public health:

• provides advice to and works with local councils and water services to reduce the number of wastewater overflows happening in our regions
• puts outs alerts to the public when there are significant risks from contact with recreational water areas contaminated by wastewater
• has a role in notifiable disease surveillance, which includes some diseases and illnesses caused by contact with wastewater.

The water from your bath, shower, kitchen or laundry is called greywater. Some of these can be used to water your garden. Greywater can be contaminated with bacteria or chemicals, so follow these guidelines to reduce health risks.

Collecting household water

Clean water

For the cleanest water, use a bucket in the kitchen sink, bath or shower to collect the water while you are waiting for it to warm up.

You can use this to water vegetables or fruit that will be eaten raw.

Greywater

Use a bucket to collect water while you shower or for after your bath.

You can also collect the rinse water from your washing machine, if you have access to the outlet pipe. Rinse water has less contaminants than the first washing cycle. But detergents may affect plant growth.

You can use this to water vegetables that will be cooked. Do not use greywater on fruit vegetables that are eaten raw, or in areas where fruit drops from a tree.

Never use water from:

• the toilet
• kitchen sink washing water
• the dishwasher as it is highly alkaline
• any source containing urine
• the laundry tub
• washing or soaking items contaminated with poo.

Tips on reusing greywater

• Store unattended buckets of recycled greywater safely away from tamariki.
• Take care that the bucket is not too heavy and that there are no spills, which can be a slip hazard.
• Only use a bucket. Talk to your council if you want to put in place any plumbing for a more permanent solution.
• Water different parts of the garden to avoid build-up of contaminants from greywater.
• Only apply greywater when and where it is needed. Avoid run-off to the surrounding area, and make sure it dries out before entering the area.
• Wash and dry your hands or use hand sanitiser after handling greywater.
• Do not store greywater — use it within 24 hours or bacteria will grow and make a bad smell.
• Do not recycle greywater when someone in the household is sick.
• Do not use greywater in areas where tamariki play.

If you see a wastewater overflow avoid it, keep tamariki and pets away and report it to your local council.

If overflow is on your property, the council may direct you to call a plumber or a drainlayer. You will need to pay for the work yourself.

Councils in Aotearoa — Local Government New Zealandexternal link

If you are planning a day in the water, check the quality to make sure it is safe.

Recreational water safety

Land Air Water Aotearoaexternal link

Safeswim (Auckland and Northland only)external link

If you have come into contact with wastewater:

• wash your hands or shower depending on the nature of contact
• wash the clothes you were wearing
• call your health provider, or Healthline on 0800 611 116, if you start to feel sick.