Nearly 500,000 households across England, Scotland and Wales are facing a critical deadline to replace their outdated energy meters before the end of June.
Those still using Radio Teleswitch Service (RTS) meters risk losing their electricity and hot water when the service is switched off on June 30, 2025.
Energy UK estimates just under 490,000 people are still using these outdated meters, which were designed in the 1980s.
The warning comes as smart meter installations have actually declined, with figures showing a 15 per cent fall in installations last year despite the pressing need for upgrades.
Customers are being urged to contact their energy suppliers to arrange an upgrade to smart meters before the deadline.
RTS meters use radio signals to switch between peak and off-peak tariffs, allowing users to access cheaper off-peak energy.
Those who do not switch could lose the heating and/or hot water GETTY They're typically found in areas with no gas supply, such as high rise flats or particularly rural houses.
Britons might have an RTS meter if their home has a separate switch box near their meter with a Radio Teleswitch label.
Another indicator is if they receive cheaper energy at different times of day, perhaps on an Economy 7, Economy 10, or Total Heat Total Control tariff.
If someone is unsure what type of meter they have, their energy supplier can confirm this for them.
Local councils have been issuing urgent warnings to residents about the impending switch-off. Glasgow council plans to deploy door knockers to directly reach affected customers.
Councillor Ruairi Kelly, convener for housing and development at Glasgow City Council, said: "It's really important that anyone with one of these meters has it replaced, as it could lead to them not being able to use their heating."
Leicester council has also sent warnings to about 4,000 residents thought to need an upgrade.
The issue affects households across various regions in Britain, with particularly high concentrations in areas reliant on electric heating systems.
Upgrading from an RTS meter to a smart meter comes at no cost to customers, as all electricity suppliers are required to offer this upgrade free of charge.
Smart meters can help households save money by sending meter readings to suppliers automatically, avoiding estimated bills.
They also allow users to track energy usage in real time, showing exactly how much is being used and when.
Households with a smart meter may be able to take part in the Demand Flexibility Service (DFS) PAAround 36 million households currently have smart meters installed. For most people, smart meters work well and can help reduce energy costs.
However, around one in 10 are thought to be "dumb" according to Ofgem data, with issues including broken displays or network connection problems.
Despite the urgent need for upgrades, smart meter installations actually declined last year.
Department of Energy Security and Net Zero figures show three million smart and advanced meters were installed in 2024, a 15 per cent drop from 2023.
By the end of 2024, 38 million smart meters were in homes and small businesses, representing approximately 66 per cent of all households and small businesses.
Data indicates six per cent of households with smart meters have them in 'dumb mode', meaning they don't send readings to suppliers.
While smart meters are not compulsory, the RTS switch-off means affected households must take action or face service disruption.
Energy suppliers are obligated to help customers transition before the June deadline.
A Smart Energy GB spokesperson noted that smart meters bring "many benefits" including helping households "manage their energy use and access energy reward schemes and flexible tariffs."
Energy bills are finally dropping but households need to take an urgent meter reading PACustomer satisfaction with smart meters has increased in the last 12 months, with more than eight in 10 people reporting they are happy with their smart meter.
The clock is ticking for those nearly 500,000 households still using outdated technology.
