This question comes from a NSW emergency management professional:

A colleague and I were having a nonsensical discussion on a water main break because the SES turned up at one. So we played semantics with the different ways the flow of water could be construed as a flood. Pretty straight forward that riverine and flash flooding gives the SES the Combat Agency role in NSW for ‘Flood’. Tsunami is included because it is specifically designated.

Now here is the issue. It is also generally accepted that SES issue warnings and response for Dam Failures. In a dam failure, the water coursing down could be considered a flood in a debate (perhaps). Prescribed dams have plans and I have not yet dived into combat agency or control agency mentions there. But in legislation, no real mention on the subject that I can find nor a specific mention in State EMPLAN.

But what of a water main break where water, and lots of it, is freely flowing down streets and through the houses? Under stand it is the water authorities problem but could it be considered a flood?

The State Emergency Service Act 1989 (NSW) s 8 says, amongst other things:

The State Emergency Service has the following functions:

(aa) to protect persons from dangers to their safety and health, and to protect property from destruction or damage, arising from floods, storms and tsunamis,

(a) to act as the combat agency for dealing with floods (including the establishment of flood warning systems) and to co-ordinate the evacuation and welfare of affected communities,

(b) to act as the combat agency for damage control for storms and to co-ordinate the evacuation and welfare of affected communities…

(d) as directed by the State Emergency Operations Controller, to deal with an emergency where no other agency has lawful authority to assume command of the emergency operation …

(f) to assist the State Emergency Operations Controller to carry out emergency management functions relating to the prevention of, preparation for and response to… emergencies in accordance with the State Emergency and Rescue Management Act 1989,

(g) to assist, at their request, members of the NSW Police Force, Fire and Rescue NSW, the NSW Rural Fire Service or the Ambulance Service of NSW in dealing with any incident or emergency…

If the SES is going to be the combat agency for floods and storms then one would imagine that what is a flood or storm is defined; but those terms are not defined.


Following the Queensland floods of 2011 an inquiry into flood insurance determined that there were problems with inconsistent definitions.  The result was that flood was defined for the purpose of insurance law (Insurance Contracts Act 1984 (Cth) s 37B; Insurance Contracts Regulations 1985 (Cth) r 29D).   For the purposes of an insurance contract, flood means:

… the covering of normally dry land by water that has escaped or been released from the normal confines of any of the following:

(a) a lake (whether or not it has been altered or modified);

(b) a river (whether or not it has been altered or modified);

(c) a creek (whether or not it has been altered or modified);

(d) another natural watercourse (whether or not it has been altered or modified);

(e) a reservoir;

(f) a canal;

(g) a dam.

So water flowing from a dam, whether it’s a dam break or a controlled release is a flood, water from a burst water main is not – at least not on your household insurance.   That does not mean a person with household insurance is not covered – they are.  A contract for household insurance must provide cover for ‘bursting, leaking, discharging or overflowing of fixed apparatus, fixed tanks or fixed pipes used to hold or carry liquid of any kind’ (Insurance Contracts Regulations 1985 (Cth) r 10).   A person that has household insurance is covered for damage caused by water escaping from the main, but only if they have flood insurance are they insured for water coming from the dam.  But that is about insurance law and is a guide, but is not the definition for the SES Act.

The Water Management Act 2000 (NSW) refers to ‘flood work’ but does not define ‘flood’.   The Water Act 1912 (NSW) s 166C also refers to ‘flood’ but gives no definition.  Neither does the Water Act 2007 (Cth).

For the Local Government Act 1993 (NSW) ‘flooded’ means ‘inundated by waters derived from the runoff of rainfall on land’ (s 3 and Dictionary).  That is a much more limited definition than the definition of ‘flood’ in the Insurance Contracts Act.

The Environmental Planning and Assessment Act 1979 (NSW) which is the Act that governs land use planning and one would hope includes provisions to limit development on flood prone land has no definition of ‘flood’.

The National Arrangements for Flood Forecasting and Warning refers to ‘types of floods’ ‘caused by heavy rainfall, although extreme tides, storm tide, tsunami, snow melt or dam break’ also cause flooding as does ‘coastal flooding as a result of sea level rise’.  The National Arrangements are concerned with ‘flooding as a result of heavy rainfall, which generally falls into the two broad categories, flash floods and riverine floods’ (see [1.2]).

In the absence of a legislative definition, lawyers start with a dictionary, traditionally the Oxford but in Australia the Macquarie Dictionary is often the dictionary of choice.  The Macquarie Dictionary (online) (relevantly) defines flood as ‘a great flowing or overflowing of water, especially over land not usually submerged’.  On that definition water from a dam or a burst water main are both a flood.

Given the variety of definitions it may be up to the Commissioner to determine what the SES functions are, and to do so in consultation with the State Emergency Management Committee.  The NSW SES website gives the following as examples of floods:

  • Rivers in Flood
  • Flash Floods
  • Dam Failure
  • Storm Surge
  • Tsunami

The NSW State Flood Plan – a sub plan of the State Emergency Management Plan, defines flood as:

Relatively high water level which overtops the natural or artificial banks in any part of a stream, river, estuary, lake or dam, and/or local overland flooding associated with drainage before entering a watercourse, and/or coastal inundation resulting from super-elevated sea levels and/or waves overtopping coastline defences.

That could include water escaping from a burst main as it would be ‘local overland flooding associated with drainage before entering a watercourse’ because the definition doesn’t refer to the source of the water but it’s destination – before entering a watercourse.


A similar definitional problem arises with ‘storms’.   When I was a member of an operational SES unit we would debate whether a ‘job’ was ours – did the tree just fall over, was their wind and if so a lot of wind?  Did it rain, if so how much?  Was there, or was there not, a storm?  Again there are no binding definitions of what is a ‘storm’.    The Bureau of Meteorology does not define ‘storm’ but it does issues severe thunderstorm warnings.  They say (‘About Severe Thunderstorms’):

Severe Thunderstorms are defined as those that produce any of the following:

  • Hailstones with a diameter of 2cm (the size of a $2 coin) or more
  • Wind gusts of 90km/h or greater
  • Flash flooding
  • Tornadoes

The SES is the combat agency for ‘storms’ not ‘thunderstorms’ and not ‘severe thunderstorms’ so that definition can’t be applicable.   The NSW State Storm Plan doesn’t define ‘storm’!    It does say, however, (at [6.1.3]):

Response operations will begin:

On receipt of an Australian Government Bureau of Meteorology:

  • Severe Thunderstorm Warning
  • Severe Weather Warning for hail, flash flooding, damaging surf
  • Tropical Cyclone Watch
  • Tropical Cyclone Warning
  • Sheep Graziers Warning

Which would suggest that by ‘storm’ the plan is limited to those severe events.  [6.1.3] goes onto say, however, that response operations will also begin ‘following impact of a storm not covered by a formal warning’. This again begs the question of ‘what is a storm?’  The NSW SES website lists the following as examples of storms:

  • Thunderstorms
  • Tornadoes
  • Tropical Cyclones and Ex-Tropical Cyclones
  • Mid-Latitude Low-Pressure Systems (including East Coast Lows)
  • Low Pressure Troughs
  • Cold Fronts and Southerly Busters
  • Cold Outbreaks

The Macquarie Dictionary defines storm as:

  1. a disturbance of the normal condition of the atmosphere, manifesting itself by winds of unusual force or direction, often accompanied by rain, snow, hail, thunder and lightning, or flying sand or dust.
  2. a heavy fall of rain, snow, or hail, or a violent outbreak of thunder and lightning, unaccompanied by strong wind.
  3. Meteorology a wind of Beaufort scale force 11, i.e., one with average wind speed of 56 to 63 knots, or 103 to 116 km/h.

So if a tree falls on a house in a mild wind or after some rain, is it storm damage?  There is no clear answer to that.

Does it matter?

One wonders if it really matters.  If we assume there is water flowing from a burst main that is threatening or doing damage to homes and businesses would we expect the SES to ‘turn out’ or refuse because it’s not a flood?

I imagine that most SES units being made up of volunteers who join to do the sort of work the SES does, and who want to help their community are willing to turn out regardless of the precise definition of flood or storm.  Further one of the functions of the SES is ‘as directed by the State Emergency Operations Controller, to deal with an emergency where no other agency has lawful authority to assume command of the emergency operation’.  The State Emergency Operations Controller is the Commissioner of Police (State Emergency and Rescue Management Act 1989 (NSW) s 18).  If the SES are directed to take charge of the response then they are in charge.

If the SES are not so directed, so for example the Local Emergency Operations Controller (State Emergency and Rescue Management Act 1989 (NSW) s 30) is taking charge then he or she could call on the SES to assist (State Emergency Service Act 1989 (NSW) ss 8(1)(f) and (g)).


There is no clear legislative definition of flood or storm.  For NSW SES the definitions have to be the ones in the relevant State sub-plan.  The definition of flood could include water from a water main.  There is no definition of ‘storm’.

I can’t however see that it matters.  Volunteers are probably willing to turn out without quibbling too much about definitions and in doing so they help build the resilience of the community that they are part of.  In modern thinking of ‘all hazards, all agency’ response whether the SES are responding as the combat agency or to assist another agency or to assist the water authority shouldn’t make too much of a difference.  Presumably the agency staff can work together to coordinate the response and if necessary identify who is to be the incident controller.  If they can’t then the Local Emergency Operations Controller is ‘responsible for controlling’ the response (State Emergency and Rescue Management Act 1989 (NSW) s 31).