How to Prepare for a Water Supply Cutoff

We turn on the tap dozens of times a day without thinking about it — drinking, cooking, washing hands, brushing teeth, flushing toilets, cleaning dishes. It's only when the water stops flowing that you realise just how completely your household depends on it.

Water cutoffs happen more often than most people expect. A burst main, contamination event, infrastructure failure, severe weather, flooding, or even planned maintenance can interrupt your supply for hours, days, or — in serious cases — weeks. In cold climates, frozen and burst pipes are a recurring winter hazard. And unlike a power outage, where most of your daily routine can be roughly maintained, losing your water supply affects almost everything.

The good news is that preparing for a water cutoff is straightforward and inexpensive. The core of it is simple: store water before you need it, know where to find additional water in your home, and have a plan for hygiene and sanitation when the taps are dry. This guide covers all three.

1. Why Water Cutoffs Happen

Understanding the common causes helps you assess your own risk and prepare appropriately.

Infrastructure failures — burst mains, pump station breakdowns, and treatment plant issues — are the most frequent cause. These can happen anywhere, at any time, and typically resolve within hours to a few days. Contamination events are less common but more serious: when a water supply is compromised by sewage, chemicals, or biological contaminants, authorities may issue a "do not use" or "boil water" advisory that can last days or longer. Severe weather — storms, flooding, and freezing temperatures — can damage pipes and overwhelm treatment systems simultaneously. Power outages disable the electric pumps that maintain water pressure in many buildings and supply networks, meaning your water can disappear alongside your electricity. And planned maintenance occasionally requires sections of a supply network to be shut down, usually with advance notice.

The key takeaway is that a water cutoff can arrive with no warning at all, or it can accompany another emergency like a storm or power failure — which makes advance preparation doubly important.

2. How Much Water to Store

If you've already built a water reserve following our guide to storing tap water for long-term emergency preparedness, you're well ahead of the curve. If not, here are the essential figures.

Plan on 3 litres per person per day for drinking and cooking as an absolute minimum. Add another 2–3 litres per person per day for basic hygiene — hand washing, brushing teeth, and minimal cleaning. That brings the practical daily minimum to roughly 5–6 litres per person.

Guidance on exact amounts varies. A common recommendation is to store at least 20 litres of drinking water per person — enough to cover minimum drinking needs for one week. Other guidance suggests a minimum of 9 litres per person (roughly three days of drinking and cooking water), or about 4 litres per person per day as a simpler daily rule of thumb.

For a household of four preparing for a one-week cutoff, that means a minimum of around 80 litres for drinking alone — more if your stored food requires water to prepare. It sounds like a lot, but 80 litres is roughly four standard 20-litre jerry cans, which fit easily under a staircase or in a cupboard.

Don't forget to account for pets, anyone with medical needs that require water (such as dialysis), and infants who may need water for formula preparation.

3. Hidden Water Sources Already in Your Home

Even if you haven't stored water in advance, there is more clean water inside your home than most people realise. Knowing where to find it can make a critical difference during an unexpected cutoff.

Your hot water tank is the most significant hidden reserve. Depending on its size, a standard domestic tank holds between 100 and 300 litres of clean water. To access it safely: turn off the electricity or gas supply to the heater, close the water intake valve at the top of the tank, open a hot water tap somewhere in the house to break the vacuum, and then drain water from the valve at the bottom of the tank into a clean container. It's one of the most reliable water sources already in your home.

Your household pipes contain a smaller but still useful amount of water. To access it, shut off the main incoming water valve (to prevent contaminated water from entering), then turn on the tap at the highest point in your home to let air into the system. Collect water from the lowest tap in the house.

Ice cubes and frozen water in your freezer are another immediate source. Melt them and use as needed.

Do not use water from swimming pools, hot tubs, radiators, home heating systems, or waterbeds for drinking — these contain chemicals or contaminants that cannot be removed by boiling or bleach treatment.

4. What to Do When You Receive a Boil Water Notice

Authorities issue boil water advisories when the water supply may be contaminated but is still physically flowing. This is different from a complete cutoff — you still have water, but it must be treated before use.

Bring water to a full rolling boil for one minute (three minutes if you're above 2,000 metres in altitude). Let it cool naturally before use. Boiled water can be used for drinking, cooking, brushing teeth, preparing infant formula, and making ice. Boiling is the most reliable method for killing bacteria, viruses, and parasites in water.

If you can't boil water (for example, during a simultaneous power outage), you can disinfect with unscented household bleach — add 2 drops per litre of clear water, stir, and let stand for 30 minutes. The water should have a faint chlorine smell afterwards. If it doesn't, repeat the dose and wait another 15 minutes.

During a boil water advisory, do not use untreated tap water for drinking, cooking, making ice, brushing teeth, washing food, or preparing baby formula. Hand washing with tap water and soap is generally considered safe during most advisories, but follow the specific guidance from your local authority.

5. Rationing and Prioritising Water Use

When your supply is limited — whether from storage, your hot water tank, or a reduced municipal flow — how you use what you have matters enormously.

Prioritise strictly. Drinking water comes first, always. Food preparation and oral hygiene come second. Basic hand washing comes third. Everything else — dishes, laundry, bathing, cleaning, flushing toilets — is either reduced to the absolute minimum or handled through alternative means.

A few practical strategies for stretching your supply: use hand sanitiser instead of water for routine hand cleaning (it's faster and uses no water at all). Switch to disposable plates, cups, and cutlery to eliminate dishwashing. Use wet wipes for personal hygiene instead of washing. And eat foods that require no water to prepare — tinned goods, crackers, nut butters, energy bars, and dried fruit are all ready to eat straight from the packet.

6. Hygiene and Sanitation Without Running Water

Loss of running water creates hygiene challenges that most people haven't thought through in advance. The two biggest are hand washing and toilet flushing.

For hand hygiene, alcohol-based hand sanitiser (at least 60% alcohol) is an effective substitute when soap and water aren't available. Stock a reasonable supply in your home emergency kit — a few large bottles will last a household several days.

For toilets, if you have no water pressure but your drains are still functioning, you can flush manually by pouring a bucket of water directly into the toilet bowl — it doesn't need to be clean water. Collected rainwater, grey water from washing, or even melted snow will work. If your drains are also compromised (as can happen during flooding), you'll need to improvise: line the toilet bowl with a heavy-duty bin bag, add a small amount of cat litter or absorbent material after each use, seal the bag, and dispose of it safely. Keep disposable gloves, bin bags, zip ties, and household bleach in your kit for this purpose.

For broader surface cleaning, a dilute bleach solution (one part bleach to ten parts water) remains effective for disinfecting surfaces even when running water is unavailable. Pre-moistened antibacterial wipes also work for everyday surfaces.

7. Protecting Vulnerable Household Members

Certain household members are more affected by a water cutoff than others. Infants who rely on formula need clean water for preparation — keep a supply of ready-to-use liquid formula that requires no mixing. People with medical conditions that involve dialysis, wound care, or medication that must be taken with water need specific planning. Older adults and those with mobility limitations may find alternative water collection (from a hot water tank, for example) physically difficult — plan for someone to assist them.

If anyone in your household depends on water-intensive medical equipment or procedures, include this in your family emergency communication plan and notify your healthcare provider about your contingency arrangements.

8. When the Water Returns

Once your supply is restored, don't immediately use the water for drinking or cooking. Authorities will typically issue a "water safe" notice, but if you're unsure, run your taps for several minutes to flush the system before using the water. The water may initially appear discoloured or cloudy — this usually clears quickly and is caused by air or sediment disturbed during the repair.

Restock your water supply immediately. Replace any stored water you used, clean and refill your containers, and recharge any purification supplies. The next cutoff won't give you advance warning just because the last one did.