Flooding here is a documented planning matter rather than local rumour. Inner West Council has been running flood studies across nine primary catchments since 2009 under the NSW Flood Prone Land Policy, and has completed overland flood studies for eight of them.
Out of that work comes something people encounter and rarely understand: a flood tag. Council flood-tags a property where a one in one hundred year event would put water more than 0.15 metres deep across more than 10 per cent of it. That tag attaches to the property rather than to the owner, and it follows the title.
A flood tag is a Council planning designation based on modelled depth and extent, and it sits with the property permanently rather than with whoever owns it. Council is the authority on what it is and what it means for any particular property. What a plumber can contribute is entirely separate and still useful: making sure the drainage on the block is doing everything it can.
- Council is the authority on tags, planning controls and what they mean
- The tag follows the title, so it is not something an owner clears
- It describes modelled overland flow, not your drainage
- Drainage maintenance helps regardless of whether a property is tagged
- Anything about insurance or a purchase belongs to your insurer or your legal adviser
On this page
1. What the tag actually is
It is a planning designation, produced from modelling rather than from anybody's memory of a particular storm. Council applies it where a one in one hundred year event is modelled to put water deeper than 0.15 metres across more than 10 per cent of the property.
Two things about that are worth understanding. It is a threshold, so a property just under it and one just over it are not in meaningfully different physical situations. And it is about the land, not the building, so it says nothing directly about how a particular house performs.
Council is the authority on all of it: what the tag is, what controls flow from it, and what it means for a specific address. Nothing on a plumbing website substitutes for asking them.
The tag sits on the property rather than the owner, so it is not something anybody clears by doing work. It is a description of the land.
2. What it is not, which matters just as much
- It is not a statement about your drainage. It describes modelled overland flow across land, not the condition or capacity of the pipework on the block.
- It is not a prediction about this year. It is a modelled event of a defined magnitude.
- It is not a defect. A great many entirely sound properties carry one, and a great many problems occur on properties that do not.
- It is not something a plumber can assess, remove or advise on. That is Council's, and any tradesperson offering an opinion on your planning position is outside their field.
- It is not the same thing as sewer surcharge, which is a separate problem covered in our guide on telling a blockage from a surcharging system.
That last distinction is the one people conflate most often, and it matters because the two have completely different remedies.
3. What actually helps, tag or no tag
This is where a plumber is genuinely useful, and it is entirely separate from the planning question. Whatever the modelling says about the land, drainage that is working is better than drainage that is not.
- Establish whether there is an overflow relief gully, whether it is clear, and whether its level is right relative to the lowest fixture inside.
- Clear every stormwater pit and grate, checking the base rather than the surface.
- Find out where each downpipe actually discharges. Some end in the ground beside a wall.
- Clear the gutters, because a full gutter overflows at the wall.
- Look at whether paved areas fall toward the building, which is common in older properties after decades of work.
- Have the drainage filmed once, so a recurring problem is diagnosed rather than guessed at.
None of that changes a planning designation and none of it is offered as though it does. All of it changes how a property behaves in ordinary heavy rain, which happens far more often than a modelled hundred-year event.
Want the drainage side dealt with properly?
We will check the gully, the pits and the discharge points and tell you what is actually there.
4. If you are buying
The tag will surface in the planning information for a property, and your legal adviser will deal with it as a matter of course. That is their field and it is not ours.
What is worth adding, and is frequently missed, is the drainage question underneath it. Does the property have a working relief gully at the right level? Where does the stormwater actually discharge? Has anything ever been filmed? Those are answerable before purchase and they are about how the house behaves in an ordinary storm rather than in a modelled one.
A building inspection generally will not cover them in any depth, which is why so many owners find out afterwards.
5. If you are renovating
Anything about how a tag affects what you may build, or what controls apply, is a question for Council and for whoever is preparing your application. Ask them early rather than assuming either way.
What is worth raising with a plumber early is levels. A great many drainage problems in this area come from ground that has been raised over the decades: paving over an old level, a new path, a deck, a garden bed built up beside the house. Each is reasonable on its own and collectively they can compromise a relief point that used to work.
So before a design is fixed, it is worth knowing where the relief gully is and what the finished levels will do to it. That is cheap to answer on a drawing and expensive to discover afterwards.
6. Who the authority is for what
- The tag, the modelling and any planning controls: Inner West Council.
- What it means for a purchase or a title: your legal adviser.
- Insurance: your insurer, and it is worth asking directly rather than assuming.
- The public drainage network: the relevant authority for that infrastructure.
- Drainage inside your boundary: yours, and this is where we are genuinely useful.
We stay in the last of those. It is a narrower contribution than people sometimes want, and it is a real one: most of what puts water in a house here in an ordinary downpour is on the property and it is fixable.
- Council has run flood studies across nine catchments here since 2009 and completed eight.
- A property is tagged where a 1-in-100 event models water over 0.15 m across more than 10%.
- The tag sits on the property and follows the title, so it is not something an owner clears.
- It describes modelled overland flow across land, not the state of your drainage.
- Council is the authority on the tag; your insurer and legal adviser on the rest.
- Gully, pits, downpipes, gutters and levels all help in ordinary rain, tag or no tag.
Flood tags and drainage FAQs
Does a flood tag mean my house will flood?
No. It is a planning designation based on modelling of a defined event across the land, and it is a threshold rather than a prediction. Council is the authority on what it means for a particular property.
Can I get the tag removed?
It attaches to the property rather than the owner and follows the title, so it is not something removed by doing work. Anything about how it applies is a question for Council.
Is it the same as the sewer backing up?
No, and conflating them leads people to the wrong remedy. A tag describes overland flow across land. Sewer surcharge is a capacity problem in the drainage system, and it has a completely different fix.
Will fixing my drainage change anything?
It will not change a planning designation and we would not suggest otherwise. It will change how the property behaves in ordinary heavy rain, which happens far more often than a modelled hundred-year event.
Should I mention it when I ring a plumber?
It is useful context, but the more useful things to tell us are practical: where water has come in before, whether it was during the rain, and whether there is a relief gully. Those change what we do.
Does it affect my insurance?
That is a question for your insurer and worth asking them directly rather than working it out from anywhere else. It is outside our field entirely.