Wastewater

The lateral pipe connects to your gully trap and direct toilet connections, taking wastewater out of your property to the public wastewater network. This pipe is your responsibility.  This pipe is buried underground and is hard to see. You will usually only realise there is a problem with your lateral pipe when it either leaks up onto the ground or blocks and comes out of your gully trap.  If this happens, please contact a plumber.

The lateral pipe can become damaged over time from tree roots growing beside or into it, land movement, or if it is accidentally damaged during construction or building works.  Take some time to know where your lateral pipe is and avoid planting trees too close or damaging it with gardening work or retaining walls. 

A gully trap is a plumbing feature that should only receive wastewater from your kitchen, bathroom and laundry. It connects to the wastewater network which carries the wastewater to a treatment plant. The top of the gully trap needs to be above ground level to prevent stormwater getting in and it should be partially covered to stop objects getting into the wastewater network but allow flow out onto the ground (and not inside your house) if your wastewater pipe does gets blocked.

The pipe from the roof should connect to the stormwater system, not the sewer/wastewater system. If the downpipes from your roof connect into the gully trap, then you will need to redirect it into the stormwater system.

Wastewater can overflow from the wastewater network into public or private property, waterways and the sea when there is a blockage somewhere in the network or if there is more water than the pipes can carry, for example after heavy rainfall. 

Although the wastewater network is separate from the stormwater network, stormwater can get into the wastewater network and vice versa when private pipes connected to the network from homes are not set up properly. This is called a cross connection.

Wellington Water is committed to helping protect our harbours, rivers and streams by reducing overflows of untreated wastewater from the networks across Wellington City, Upper Hutt City, Porirua and Hutt City.  We’re working in two different areas:

• Reducing wet weather overflows caused by rainfall entering the wastewater network
• Reducing dry weather overflows, which are mainly caused by blockages in older pipes. We’re trialing smart manholes to tell us when there a blockage before it overflows into the street, private property or river and we are increasing our work to replace aging pipes across the network.  You can help reduce blockages by only putting the three P’s into your toilet. 

Overflows during heavy rainfall

For overflows during heavy rainfall, we have historically managed these on a case-by-case basis.  Community and mana whenua expectations for water quality are increasing and we want to move to an improvement strategy, where we assess priorities for investment across the whole network.

We’re working on a process for formalising this in resource consents – one for each city's wastewater network:

• Porirua including North Wellington
• Hutt Valley including Upper Hutt and Wainuiomata
• Wellington including Karori

The consents would set out a collaborative process with mana whenua to:

• Set future network standards – that is, the volume of overflows we should aim for, taking into account costs and benefits
• Recommend priorities for improvement.

We’re also proposing community involvement in the process.

The consents will take decades to implement and may involve significant investment from our Councils and ratepayers.  Unfortunately, there is no quick fixes or cheap and easy solutions.  But we know its important work and we are committed to it.

We’ll provide updates on this work here, as it progresses.

One way to help keep our streams, coast and harbours clean for generations to come is to ensure there are no cross connections or wastewater faults on your property - they don’t comply with the Building Act and can cause pollution. Cross connections can cause stormwater to get into the wastewater network. During heavy rainfall, this increases the volume of water and can overload the network’s capacity, which can result in overflowing gully traps, manholes, pump stations, and engineered overflow points into streams, rivers and the sea. 

It is the homeowner’s responsibility to ensure their drainage pipes connect to the right system and are properly maintained. If you are getting drainage work done for an extension or new development, ensure your drainlayer is 100% confident your pipes are going where they should and there are no cross connections.

To avoid wastewater overflows ensure you are only connecting wastewater plumbing to your gully trap. Any outside stormwater, including from roofs, retaining wall drains, driving strip drains, basement pumps or paved area drains, must be diverted to a soak pit or stormwater pipe to road kerb.

Wastewater connections to stormwater pipes have an even more harmful impact. If there is a faulty connection or leak, untreated wastewater can end up directly in the stormwater system and straight into our streams, rivers and the sea until the fault gets repaired. 

More information

For more information, visit https://www.level.org.nz/ Level is the authority on sustainable building, and they have useful information about the compliance requirements for drainage on properties.

Whenever you flush a toilet, have a shower, or unplug a sink, that water flows through your plumbing and into the public wastewater network. It's important that we all look after the region's wastewater network to avoid blockages that take time and money to fix. The two most common things we see in our wastewater network that cause blockages are cooking oil and wet wipes. 

‘Rag Monsters’ - are made up of wet wipes, tampons, sanitary pads, nappies, cloth, hair and other non-biodegradable material, and they should never be flushed down the toilet.

They can block up wastewater pipes – which could cost you a lot of money in plumber bills to repair if the damage happens within your property boundary. If wet-wipes or other items manage to make it all the way to the wastewater treatment plant, they end up blocking the screens at the plant (which may have to be cleared by hand).

These items have no place in the wastewater system and should never be flushed down the toilet.

Put unflushable items into your rubbish bin, and only flush the 3Ps down the loo - pee, poo and paper (toilet paper that is)!