Energy-efficient hot water

How much energy do I use to heat my water?

In a typical household, 12% of the energy bill goes on water heating, according to the Energy Saving Trust. This may seem low, compared to heating your home, but since you need hot water all year round, it soon adds up. 

Older systems are less efficient. They use more energy to produce the same amount of hot water and that percentage is likely to be higher. 

The true cost of hot water also depends on how much you pay for your water supply. Industry regulator Ofwat has confirmed that the average water bill in England and Wales is set to rise by 36% in the next five years to 2030. Depending where you live, this could be an annual increase of £200+. 

Installing a water meter, which is free in most cases, can help you track your usage more accurately and highlight where you could make savings. Ensuring you’ve got a high-efficiency hot water tank is another way to cut costs. If you can’t upgrade to a newer model, adding extra insulation is a cheaper alternative.

What’s the most efficient way to heat hot water?

Introducing a more energy-efficient water heater starts with understanding how your hot water system works:

Central heating

In the UK, most homes traditionally use a central heating system to heat water, which is stored in a hot water tank. This might run on gas or electricity - with gas being the cheaper but less flexible option.

A fixed amount of water is heated so energy is wasted if the water cools before it’s used. 

Immersion heaters

Immersion heaters provide a hot water back-up. They work like a kettle, using electrical elements to heat water, and can be switched on when needed. They can be expensive to run unless you’re using solar power. 

Combi boilers

A more modern and energy-efficient water heater, combi boilers heat water on demand directly from your mains water supply. They don’t need a hot water cylinder or cold water tank. They’re also perfect for smaller homes, as you don’t need space for a separate hot water tank. Combi boilers run on oil, LPG (Liquified Petroleum Gas), or electricity. 

Compare the pros and cons of different fuel types in our guide to gas, oil and other home heating fuel.

Electric showers

Also offering on-demand hot water, electric showers don’t rely on the main hot water supply. Installation costs depend on the make and model. 

According to Checkatrade:

• A standard low-range shower costs £150 with £200 in labour
• A top-of-the-range digital shower can cost £1,000 plus £300+ for installation.

Solar water heating systems/solar thermal systems

Using heat from the sun, solar water heating systems are designed to provide the hot water you use for bathing, showering and hot taps rather than 100% of your household’s hot water.

If you haven’t already got solar panels installed, it’s worth researching possible set-up costs. 

Heat pump water heater 

Heating water with green energy, heat pump water heaters are increasing in popularity in the UK. They draw heat from natural sources and include: 

• air source heat pumps
• ground source heat pumps
• water source heat pumps.

How much energy does a shower use?

Showering is considered more energy efficient than taking a bath, but it’s also something most people do every day. Making changes to your shower habits is a good way to save money and improve your energy efficiency.

Showers fall into several categories:

• Manual mixer showers use water straight from the hot and cold taps with no electrical heating involved. They're suited to homes with high water pressure. Their typical water consumption is three to eight litres per minute
• Thermostatic mixer showers are like manual mixer showers, but with a built-in thermostatic valve to keep the water at a constant temperature
• Electric showers run off the cold water supply and heat water by passing it through an element in the shower unit. Their typical water consumption is eight litres per minute 
• Power showers draw hot water from the hot water tank and mix it with the cold-water supply, so it relies on a central heating system or immersion heater. Their typical water consumption is four to five litres per minute.

Water consumption can vary considerably due to other factors, including:

• The make and model of your shower
• The type of shower head
• Water pressure (high or low)
• Shower hose - whether it’s kinked or damaged causing leaks
• How long you spend in the shower.

What type of shower is most cost-effective?

As gas costs far less than electricity under the current energy price cap, a mixer or power shower should be more cost-effective than electric. 

However, electric showers usually use less water and therefore less energy. They heat water at the point of use, making them more efficient than power and mixer showers which lose heat in the tank and pipes.

Electric showers cost less too, if you’re on a water meter.

How much does an electric shower cost to run?

Under the January 2025 price cap, an electric shower costs an average of £3.73 per week, or £193.91 a year. 

This can vary depending on how many people shower, how often they shower, and how long they spend there. 

A YouGov survey revealed that 49% of UK adults shower one a day, 5% twice and 1% more than twice.

Uswitch research suggests people spend an average of around 7 to 10 minutes in the shower. According to the Energy Saving Trust, reducing shower time to four minutes could save a typical household £60 a year.

What can I do to lower my water heating costs?

Here are some straightforward ways to lower your water heating costs:

1. Choose carefully how you heat water.
2. Be sensible about when you heat hot water.
3. Use less hot water.
4. Heat your hot water to a lower temperature.
5. Don't let hot water cool down before you have used it.

Top free tips to save on your water heating

• Turn down the thermostat on your cistern to 60-65°C
• If you have an old central heating system, the temperature of the hot water will be determined by the internal circulatory system, as set on the boiler, so turn that down
• Use a kettle for the times you need very hot water
• Check the timings and other controls on your boiler for your water heating, which on an older boiler will often be integrated with the timings of your central heating. You may be able to reduce the length of time that the water heating is turned on, especially in the summer
• Check to see if your power shower pump has flow controls. If it does, you should be able to reduce the flow
• With any type of shower, check to see if you can adjust the shower head spray pattern - you may find that you can reduce the flow of water
• If you wash up by hand, don't rinse the dishes under running hot or cold water. Instead, use a separate bowl
• If you have an older boiler it's a good idea to use an immersion heater in the summer.

Small investments to help save on your water heating

• If you have an old cistern (tank) that isn't insulated, then fit a tank jacket.
• This should pay for itself in just a few months and you can add to the insulation effect by storing bedding, pillows and towels around the cistern
• Where they're accessible, insulate the 'downpipes' - these are the pipes that lead from the cistern to the taps
• If you have a mixer or power shower, fit a shower head flow regulator or a shower head that aerates the flow. Both reduce the flow of water, cutting water and energy use
• If your hot water is solely or often heated using an immersion heater and you don't already have a timer on it, it's a good idea to fit one. This is particularly useful if you have an Economy 7 supply, as it means you will be able to heat your water using overnight cheap electricity
• Fix dripping taps. If you don't feel confident putting new washers in your taps, you could ask your plumber to do it
• Buy a shower timer to check how long you're really spending in the shower
• Make sure your shower is in good condition, including the shower head, the hose and the wall mounting. Replace parts if necessary and de-scale your shower head regularly if you live in a hard water area, otherwise scale build-up will affect the water flow.

Moderate to high investments to help save on your water heating

• If your hot water cistern is very old, consider replacing it with a modern insulated one.
• Water can stay warm for up to two days and it could perform much better even compared to an old-fashioned tank with a jacket on it
• If you're thinking of installing a solar hot water system in the future, it may be worth installing the larger-sized tank with the required two heat inputs - one for the central heating and one for the solar panel
• If your boiler is over fifteen years old, it could be time to replace it. A modern combi-boiler, which provides instant hot water, is generally considered to be more energy efficient than a 'stored' hot water system
• You could install solar water heating (SWH), also known as solar hot water (SHW).
• This is an expensive measure, but the introduction of the Boiler Upgrade Scheme by the government could provide you with a grant to bring the installation costs down.

How does solar water heating work and should I install it?

Solar water heating systems circulate liquid through a panel. This liquid is warmed by the sun, even on cloudy days, and circulated through the hot water tank, warming the water.

This panel should ideally be on a south-facing roof, a wall or a ground-mounted system. There are two kinds of panel:

• Flat panel
• Evacuated tube, the more expensive and efficient option

Your existing boiler then tops up the heat when it’s needed.

Using existing solar panels

Rather than adding a solar hot water system to existing panels, you can use a solar immersion heater with an electric energy-efficient water heater. 

There are times during the day when your solar panels will generate more energy than you can use. If you don’t have a solar battery to store the excess, it’s sent to the National Grid. A solar power diverter automatically diverts the energy to the immersion heater.

While not the most efficient way to heat a hot water tank in the UK, solar immersion heaters can provide eight to nine months of free hot water a year. You keep more of the energy you make and don’t lose money to the grid.

Should I install a heat pump water heater?

Heat pumps sit under the umbrella of green energy. They run on electricity from renewable sources which is good news for the planet. 

Heat pump water heaters are an energy-efficient way to heat your water. However the upfront costs mean they’re not necessarily the cheapest option in the short term.  

Heat pumps work in a similar way to your boiler, but instead of burning fuel they draw on heat from the air, underground, or water. They then transfer the heat to water inside a cylinder or tank.

Hybrid heat pumps combine an air or ground source heat pump with a gas or oil boiler. 

If installation costs are an obstacle, it’s worth looking into a Green Deal finance plan.

Find out more about heat pump water heaters.

When’s the best time to replace my hot water system?

Most boilers are designed to last around 15 years. If yours needs replacing, now is a good time to consider a combi boiler or other energy-efficient way to heat your hot water tank, such as solar power or using a heat pump.