Stormwater
Introduction |
About stormwater |
Solving stormwater problems |
Growth and stormwater |
What Auckland City is doing |
Stormwater projects near you |
Stormwater assets |
Stormwater guidelines and other documents |
Educational information
Stormwater stories
Silly things we often see
Click on the numbers in the image below for examples of silly things. Use the
back button on your browser to return to the image.
More silly things.
Flooded driveway and garage
Building in an excavation is an invitation to trouble - and installing
or improving sloping driveways can be too:
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Water that gets into a building constructed in a
hole can't get out. |
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Steepened or lengthened driveways may divert runoff
into your home or garage. |
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Think about stormwater runoff when doing your home
improvements to avoid the distress of water flowing into it. |
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Auckland City's approval
processes are there to keep you safe by advising about overland
stormwater flow paths, letting water escape and ensuring that cut
slopes are not dangerously high. |
A good gully trap - wastewater only
Stormwater and wastewater need to be kept apart so that stormwater gets
to the nearest water body, and wastewater gets to the Manukau sewage
purification plant without overflowing from pipes on the way.
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If too much
stormwater gets into the wastewater pipes, they can overflow through
manhole lids and pump stations - and sometimes back up through toilets
or sinks in people's homes. |
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To avoid
wastewater overflows, make sure the downpipe from your gutters goes into
the stormwater system, not your gully trap, and |
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Make sure the
wall around the trap is high enough to keep stormwater out. The Building
Act requires the top of a gully trap (or a gully trap surround) to be at
least 25mm above surrounding paved ground and 100mm above surrounding
unpaved ground. |
Overland flow path
Gravity is bigger than all of us - so we need to
respect the natural law that makes water flow downhill:
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If you block an overland flow path, this will divert
the stormwater flow elsewhere - probably where it is not wanted,
such as into your house or in concentrated flow onto neighbouring
properties. |
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Click here to find
out more about your responsibilities for stormwater on your land. |
Recycle your rubbish
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Tipping debris
like grass clippings, other garden wastes and unwanted items into
streams and gullies creates dangerous log-jams in heavy rain. |
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Large amounts of
water can sweep accumulated debris down gullies, blocking channels,
culverts and pipes. When the debris stops, the water flows over it,
creating flooding downstream. |
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Compost or use a garden rubbish collection for garden waste and use
inorganic collections for the rest. |
Trees blocking stream
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Trees beside
watercourses are great for erosion prevention and for native fish like
whitebait and eels. |
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Trees in
watercourses are bad news in wet weather, obstructing flow and
causing back up of flood waters onto property. |
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Regularly inspect
your private watercourse and nip out those encroaching trees while they
are still small. |
Emptying your swimming pool
Chlorine kills bugs - that's what it's meant
to do to keep your swimming pool healthy:
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Unfortunately,
chlorine can also kill fish in your local stream if you empty your pool
straight down the stormwater grate. |
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Choose one
of the following two simple ways to avoid the problem:
- empty the pool into the waste water system
through the gully trap (you will have already paid for the charges at
the time of filling the pool)
- if you can't reach the gully trap, take the
cover off the pool for two weeks to let the sun break down the
chemicals (don't add any more) then let the water out it into
the stormwater grate. This will avoid killing fish below the outfall.
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Some other examples of silly things
Flooded living room
| Filling in the basement to create a granny flat or home office seems a
good idea: |
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Except the water that used to
flow harmlessly across the back of the section now flows across your
carpet. |
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Obtain a building consent and always check stormwater flow paths
before building on lower levels of your property. |
Contact us about developments on your property such as a new carport or
extra bedroom so we can advise you about stormwater and prevent harm to
your property and others around you.
Walls and floorings damaged by flooding
| Level access is great for push chairs, wheelchairs
and older people: |
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But it can
sometimes let water get inside. |
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Remember that the
floor level of your house needs to be at least 150mm above ground to
keep water out. |
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When you start
creating your dream garden on a new section, keep that nice new topsoil
at least 150mm below your floor level to save your new carpet from
flooding! |
Concrete kills and concrete clogs!
It's made to set like rock:
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And that's just
what some surplus concrete did when poured into a stormwater grate at
the end of a job. The blockage prevented stormwater runoff from getting
into the pipe, causing flooding. Concrete is also very alkaline (the
opposite of acidic) and kills fish quickly. |
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Always scrape out
surplus concrete from equipment onto a temporary place where it can set
solid for recycling or disposal to cleanfill or landfill. |
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Put washwater
onto the lawn or construction gravel areas where it can soak into the
ground and not run off into stormwater. |
Illegal filling along the edges of watercourses
Adding to your property asset by filling soil or
other materials along a stream bank may seem a good idea - but valleys
are a natural feature mainly formed by storm flows that occur roughly
every 2-5 years.
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These frequent
floods could scour out your fill and any improvements like decks and
fences sitting on it, which would clog up downstream passage of the
flood water. |
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Restricting the
channel by filling its banks could also cause flood waters to back up
and flood your property and that of your neighbours. |
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Keep your stream
banks in a natural state to help the stream do its job of carrying water
safely to the sea. Click here to find out more on caring for your
stream. |
Building over stormwater inlets
Stormwater grates direct surface runoff into the piped
stormwater network to prevent flooding.
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Building over a
grate interferes with how the natural fall of the land funnels
stormwater towards the grate for prompt removal. |
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Always ensure
water can get into the stormwater system by keeping overland flow paths
and stormwater inlet grates clear. |
Clogging up stormwater soakholes
In volcanic areas, the underlying rock is too hard
to easily install stormwater pipes. Fortunately, it is so porous that
soakage systems allow stormwater to naturally seep away into the ground.
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Keep those soakage areas clear of debris that clogs
them up and stops the water getting away. |
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Have a plumber clean the soakage system every two
years. |
Click here to find out more about keeping your stormwater soakage
system operational.
Filling in stormwater soakholes
Not knowing what that shallow area in the back yard is for could literally
pave the way to a flood of problems.
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Paving over or filling in stormwater soakage systems
means rain that lands on your property cannot easily soak away into
the basalt rocks below. |
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Maintain and protect your on-site soakage so it can
do its job of keeping your and your neighbours' land safe from
flooding. |
Removing on-site devices
Not sure what that tank, pipe or channel is for?
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Contact us
before you take it out - it could be an on-site stormwater device
designed to protect your property and that of your neighbours from
flooding. these devices keep stormwater on your property for long
enough to prevent the system from overloading and flooding
downstream. |
Infill and intensification pose a risk to existing infrastructure like wires,
gas lines and water services pipes:
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Before you start your site excavations, trenching or
piling, contact us to
find out what the reticulated services are on or near the site to
make sure you work around them. |
Leaves blocking stormwater inlets
| The attractive deciduous trees in many suburbs create real problems in autumn
and winter as they shed their leaves and clog stormwater inlets. |
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Rake them up while they are dry to make sure water on
your property can get to the stormwater system instead of flowing
overland and causing flooding. |
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Better still, plant natives - they don't shed leaves
and planting female instead of male [plants will also keep down
those nuisance pollen levels in hay fever season! |
Planting trees and shrubs for privacy
Trees and shrubs increase the appeal and privacy of our properties, but:
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Water-seeking roots can damage pipes, resulting in
expensive damage. |
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Take care to plant shrubs at least 1.5m away from
buried stormwater pipes |
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Click
here to find out how to get plans showing where drains are on
your land. |
Mud from a building site
| Sediment is one of Auckland's number one pollutants. Erosion
during construction ruins your section, making it hard to establish
gardens. Sediment coats paths and roads in fine sticky clay and clogs up
the stormwater system before ending up on the local beach. |
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Ask your builder to minimise the area of exposed soil
and to install a silt fence to keep any that runs off during rain on
your site where it belongs, |
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Simple things we all can do
Below are examples of some simple things we can do to manage stormwater on
site. Click here for more simple things you can do.
Auckland City is playing its part too, click here to
find out more about Auckland City's own innovative projects.
