When the Water Goes Off
Two things surprise people about losing water.
The first is that it often arrives with a blackout rather than a burst main. Mains pressure usually survives an outage, but pumps do not — so apartments above a certain height and any property on tank water lose supply the moment the power goes.
The second is how much of daily life turns out to be water. Not drinking, which is a small volume. Flushing, washing, cooking and cleaning, which is most of it.
The 10-minute version
- Fill everything at the first warning. Bath, laundry trough, sinks, pots, bottles. Free, takes four minutes, and it is the whole difference.
- Drinking water: 3 litres per person per day. Everything else — flushing, washing — can be non-potable, and a full bath covers a surprising amount of it.
- A boil water notice means a rolling boil for one minute, and it applies to more than drinking: teeth, ice, salads, baby formula and pet water.
The numbers
| Use | Volume | Notes |
|---|---|---|
| Drinking | 3 L per person per day | More in heat, or if pregnant, unwell or breastfeeding |
| Basic cooking | 2–3 L per day per household | Can be the same stored water |
| Toilet flush | 4–9 L per flush | Non-potable. A bucket poured fast does it |
| Sponge wash | 3–5 L per person | Non-potable |
| Washing up | 5–10 L per day | Non-potable |
| Three-day store, family of four | 36 L drinking | Plus a filled bath for everything else |
That table is why the bath matters. Drinking water is a small, easily stored volume. It is flushing that consumes it.
Where water already is in your house
Before going anywhere, you probably have several hundred litres.
Safe without treatment:
- Stored bottled water
- The hot water system — typically 100–300 litres. Turn off its power or gas first, then drain from the bottom valve. It runs rusty at first
- Ice in the freezer
- Liquid in tinned fruit and vegetables
Usually safe, treat if unsure:
- The toilet cistern — the tank, never the bowl — if there is no blue cleaner or chemical block in it
- Rainwater tank, if the catchment is clean. Boil it if anyone drinking it is very young, elderly, pregnant or immunocompromised
- Water left in the pipes: open the highest tap to let air in, collect from the lowest
Non-potable but useful:
- Pool water, for flushing and washing only. Never for drinking — the chemistry is not designed for it and boiling concentrates it
- The bath you filled before the outage
The toilet protocol
The part nobody writes about and everybody needs.
- A bucket of any water poured quickly into the bowl flushes it. Four to nine litres, poured fast rather than trickled.
- Do not flush for every use. Liquid waste can accumulate; solid waste gets flushed.
- If there is no water at all, line the bowl with a heavy-duty bag, use kitty litter or sawdust to cover, tie off and bin. Unpleasant, hygienic, and far better than the alternative.
- If you are on a septic system with a pump, be sparing — the pump is out too.
- Hand hygiene matters more than usual. Alcohol-based sanitiser is the low-water option, and it is worth having a bottle in the kit.
Boil water notices
Issued when the supply may be contaminated — after flooding, a main break, or a treatment failure.
What it requires: bring water to a rolling boil for one minute, then let it cool in a covered container. An electric kettle that switches off at boil is sufficient.
What it applies to, and this is the part people miss: drinking, brushing teeth, making ice, washing fruit and vegetables eaten raw, baby formula, pet water, and rinsing anything that goes in a mouth.
What it does not require: boiling water for showering (avoid swallowing), laundry, or flushing.
Bottled water is an alternative to boiling for all of the above.
When it lifts, run your taps for several minutes, discard ice made during the notice, and clean and refill water filter jugs.
If chemical contamination is suspected rather than biological, boiling is not the answer — it concentrates chemicals. Follow the specific advice issued, which will usually be to use bottled water only. Method comparisons are in How to Find and Purify Water.
Apartments, and why they lose water first
If you live above roughly the third or fourth floor, your water arrives via a pump. No power, no pump, no water — often within minutes, once the header tank empties.
- Fill containers the moment the power goes, not after discovering the tap is dry. You may have only a few minutes of stored pressure.
- Keep 9 litres per person stored permanently. In a unit that is two 6-litre bottles per person on a cupboard floor.
- The building’s pump may be on the strata’s emergency plan. Worth asking, because some buildings have a generator for exactly this.
- Lifts are out too, so carrying water up stairs is the realistic scenario. Store it upstairs, not in a garage.
Full version: Blackout Plan for Apartments.
What actually goes wrong
Nobody fills anything. Four minutes, free, and skipped.
Only drinking water is stored, so the household is fine for water and cannot flush.
The hot water system is forgotten — 200 litres of drinkable water, in the laundry, unused.
People drink from the pool.
The boil water notice is applied only to drinking, so teeth get brushed with contaminated water.
Water is stored in a garage or basement in an apartment, where the lift is out.
Sanitiser is missing, so hand hygiene collapses at exactly the wrong moment.
Stored water is years old. Rotate it six-monthly.
Thresholds
| Situation | The rule |
|---|---|
| Any storm or outage warning | Fill bath, trough, sinks, pots and bottles immediately |
| Blackout in an apartment or on tank water | Fill containers within minutes — pressure is finite |
| Drinking water | 3 L per person per day, three days minimum |
| Flushing | Any water, poured fast. Do not flush every use |
| Boil water notice | Rolling boil, one minute. Applies to teeth, ice, raw produce, formula and pets |
| Suspected chemical contamination | Do not boil. Bottled water only, and follow the specific advice |
| Notice lifted | Flush taps, discard old ice, clean filter jugs |
| Stored water | Dated and rotated every six months |
What it costs
| Tier | Spend | What it buys |
|---|---|---|
| Free | $0 | Filling everything at the first warning, knowing how to drain the hot water system, the toilet bucket method |
| Solid | ~$30–60 | 9 L per person in bottles, a 10 L collapsible container, a bottle of hand sanitiser, heavy-duty bags and kitty litter |
| Better | ~$120–200 | A 40 L drum with a tap, a bathtub bladder that turns a bath into clean stored water, a certified filter for uncertain sources |
The bathtub bladder is an underrated item for apartments and flood-prone houses: it lets you store 100 litres of clean water in a bath rather than 100 litres of bath water.
The drill: the twenty-minute practice
- Five minutes. Find and operate the drain valve on your hot water system. Turn its power or gas off first, drain a litre onto the garden, and note where the valve is.
- Five minutes. Fill the bath and the trough as if a warning had just been issued. Time it, so you know it is four minutes rather than an afternoon.
- Five minutes. Practise the bucket flush once. It is not obvious that speed matters until you try it.
- Three minutes. Check your stored water dates and rotate anything older than six months.
- Two minutes. Put the sanitiser, bags and litter with the kit, and tell the household where they are.
Frequently asked questions
How much water should I store per person?
Three litres per person per day for drinking, three days minimum — nine litres each. Store non-potable water for flushing and washing separately, and fill the bath when a warning is issued.
Why does my apartment lose water in a blackout?
Because water above roughly the third or fourth floor is delivered by an electric pump. When the power fails the pump stops, and supply ends once stored pressure runs out — often within minutes.
What does a boil water notice actually cover?
Drinking, brushing teeth, making ice, washing raw fruit and vegetables, baby formula and pet water. Bring water to a rolling boil for one minute. Showering is fine if you avoid swallowing, and laundry and flushing are unaffected.
Can I drink pool water in an emergency?
No. Use it for flushing and washing only. Pool chemical concentrations are not designed for drinking and boiling concentrates them further.
How do I flush a toilet with no running water?
Pour a bucket of any water — four to nine litres — into the bowl quickly. Speed matters more than volume. Do not flush every use; save it for solid waste.
Where can I find water inside my house?
The hot water system holds 100–300 litres of drinkable water, plus ice in the freezer, the toilet cistern if it contains no chemical cleaner, and water remaining in the pipes if you open the highest tap and collect from the lowest.