Could a Cyberattack on the Power Grid Stop Your Water Supply?
As part of Preparedness Month, we take a look at how an extended loss of power could affect your tap water.
When we think about a power cut, we all tend to picture dark houses, dead phone batteries, and a freezer slowly warming up. What we may not immediately think about is the faucet.
But electricity and water supplies are closely connected. Modern water systems need power to extract, treat, pump, and distribute drinking water. This means that a major disruption to the electricity grid – whether caused by severe weather, equipment failure or a cyberattack – could potentially become a water emergency too.
And cyber threats to critical infrastructure are receiving increasing attention. The UK's National Cyber Security Centre (NCSC) has warned of increased targeting of the operational technology used to control essential infrastructure. (National Cyber Security Centre)
Why does a water supply need electricity?
Getting clean water to your tap involves much more than simply allowing water to flow through a pipe.
Depending on the water source and local system, electricity can be needed for:
- pumping raw water from rivers, reservoirs or groundwater sources
- running water-treatment equipment
- chemical dosing, filtration and disinfection
- operating pumps that maintain pressure in the distribution network
- monitoring reservoirs, pumping stations and pipelines
- operating computerised control and communications systems.
The NCSC describes modern water infrastructure as a network of treatment facilities, reservoirs, pumping stations, programmable controllers and central monitoring systems, all of which need to operate continuously and reliably. (National Cyber Security Centre)
That creates an important dependency: no electricity can eventually mean no water.
What would happen if a cyberattack took down the electricity grid?
The effects would depend enormously on where the outage occurred, how widespread it was and how long it lasted.
A brief local power cut is unlikely to mean your taps immediately run dry. Water companies build resilience into their systems, and facilities may have reservoirs, generators and other backup arrangements.
A prolonged or widespread blackout is different.
1. Water treatment could be disrupted
Treatment plants use electrically powered equipment to turn raw water into safe drinking water. If power were unavailable for long enough and backup systems were exhausted or unavailable, treatment capacity could be reduced.
For safety reasons, a water company may have to stop supplying water from a facility rather than risk distributing water that hasn't been properly treated.
2. Pumps could stop working
Water doesn't always travel to our homes by gravity. Pumps are needed throughout many distribution networks.
The US Environmental Protection Agency (EPA), which publishes extensive guidance on power resilience for water utilities, warns that power outages can have significant effects on drinking-water and wastewater operations. (US EPA)
If pumping stations lose power, water pressure could gradually fall, and some areas could lose their supply altogether.
Homes at higher elevations or at the extremities of a network could potentially be affected before others.
3. Low water pressure could create another problem
Losing pressure isn't simply inconvenient.
Water mains are normally pressurised partly to keep unwanted material out. According to the EPA, loss of pressure can allow contaminants from surrounding soil or groundwater to enter a drinking-water distribution system. (EPA NERL)
This is one reason why, following certain disruptions, authorities may issue precautionary advice about drinking tap water even after supplies have been restored.
4. Wastewater systems could also be affected
There's another side of the water system we rarely think about: what happens after water disappears down the drain.
Sewage systems also rely heavily on pumps and treatment facilities.
A prolonged electricity outage can therefore interfere with wastewater treatment and pumping. In severe circumstances, pump failure can contribute to sewage backing up or untreated wastewater being discharged into the environment. (EPA NERL)
So a major power outage could potentially affect both clean water coming into our homes and wastewater leaving them.
What makes a cyberattack different from an ordinary power cut?
The physical consequences of losing electricity may be similar, whatever the cause. What makes a serious cyberattack potentially more complicated is recovery.
An electricity company dealing with storm damage may be able to identify damaged equipment quickly and repair it within a few hours. A cyber incident could potentially affect computer networks, communications and operational technology at the same time. That can take longer to find the source of the attack and eliminate it.
There is real-world precedent for cyberattacks disrupting electricity infrastructure. The NCSC has documented how attackers gained access to Ukrainian electricity distribution networks in an attack that resulted in power outages affecting around 250,000 people. (National Cyber Security Centre)
The UK Government published a new Energy Sector Cyber Security Strategy in May 2026 specifically aimed at strengthening the cyber security and resilience of Great Britain's energy system. (GOV.UK)
Water infrastructure itself can also be targeted. In July 2026, the US Cybersecurity and Infrastructure Security Agency warned of increased targeting of programmable logic controllers used by water and wastewater organisations. Some incidents had resulted in boil-water notices and utilities having to operate systems manually. (GovDelivery)
This doesn't mean that a nationwide cyber-induced blackout is imminent. It does demonstrate why governments increasingly regard cyber resilience as part of protecting critical infrastructure.
Would the water stop immediately?
Probably not.
Water systems contain storage, and utilities can have emergency generators and contingency arrangements. The EPA, for example, specifically advises water utilities to plan their emergency generator requirements so that essential operations can continue during electricity failures. (US EPA)
But resilience isn't unlimited.
The longer and more widespread an electricity outage becomes, the greater the potential challenge of maintaining water treatment, pumping, and distribution.
That is why household emergency planning shouldn't concentrate solely on keeping the lights on.
How much emergency water should you keep at home?
Having a modest emergency water supply gives you a buffer if mains water is temporarily unavailable.
Rather than waiting until an emergency – when bottled water can quickly disappear from supermarket shelves – keep a sensible quantity of drinking water at home as part of your general emergency supplies.
Remember to think beyond drinking. Water may also be needed for preparing food, taking medication and basic hygiene.
Your emergency plan could include:
- a stored supply of safe drinking water
- clean, food-safe water containers
- a water purifier for treating additional water if your stored supply runs out
- knowledge of potential alternative water sources in a longer emergency
- a battery-powered or wind-up radio for official information
- torches, power banks and essential medication.
Stored water should be protected from contamination and checked periodically. Our blog 'How to Store Water at Home' tells you how.
What if your stored water runs out?
This is where emergency water purification can provide an additional layer of resilience.
In a prolonged disruption, water might still be available from alternative sources – such as collected rainwater or other freshwater sources – but available water isn't necessarily safe water.
Microorganisms can make apparently clean water unsafe to drink. A suitable water purifier can therefore give a household more options if normal drinking-water supplies are interrupted.
However, it's important to understand the limitations of any purification system. Different technologies remove different contaminants, and water suspected of containing fuels, industrial chemicals, heavy contamination, or toxic substances shouldn't automatically be assumed safe simply because it has passed through a portable purifier. Graphene-enhanced purification will give you more options should the need arise.
Always follow official emergency advice about local water sources.
Preparing for a cascading emergency
One of the most useful lessons from emergency planning is that infrastructure doesn't operate in isolation.
Electricity powers communications. Communications support emergency services. Electricity powers water treatment and pumping. Hospitals, businesses and households need water.
A disruption that begins in one system can therefore spread into others.
You don't need to prepare for every imaginable disaster individually. Preparing for the consequences is often much simpler.
So ask yourself: if the power went off and the taps eventually stopped running, could your household manage comfortably for a few days?
Keeping emergency drinking water, a reliable means of purification and a few basic supplies at home can provide valuable breathing space – whether the original cause is a cyberattack, storm, flood, infrastructure failure or something nobody saw coming.
For more advice on emergency water purification, get in touch.
