Key points
- Water heaters are among the products that must carry an energy efficiency label in Saudi Arabia under SASO 2884; covered products may not be offered without the label.
- Legionella bacteria multiply between roughly 20 and 45°C.
- UK HSE guidance: store hot water at 60°C or above, distribute at 50°C or above, and keep cold water below 20°C.
- To prevent scalding at outlets, thermostatic mixing valves (TMVs) are fitted close to outlets where there is a risk.
The water heater is one of the most important appliances in the home. Its type determines your electricity bill and comfort, and setting its temperature is a health decision before it is a comfort decision: there are two opposite risks, bacteria if the temperature is low, and scalding if it's high at the tap.
Types of water heater and how to choose
| Type | How it works | Suits | Watch out |
|---|---|---|---|
| Tank heater (one per bathroom or kitchen) | Heats water and stores it in an insulated tank | Most homes; simple installation | Loses some heat while standing; its size limits the hot water available |
| Central tank heater | One tank feeds several outlets | Large homes with a designed hot water network | Longer pipes = longer wait for hot water and more heat loss; needs network design |
| Tankless (instantaneous) | Heats water as it flows | A single nearby outlet, or tight spaces | Electric models need high electrical capacity with suitable cables and breaker; ask an electrician before buying |
| Heat pump water heater | Moves heat from the air into the water instead of generating it directly1 | Owners who want lower electricity use | Needs an interior space with enough air, cools the space it is in, and may need annual filter maintenance2 |
| Solar water heater | Collectors gather the sun's heat, with an electric or gas back-up heater3 | Homes with a sunny roof and enough space | Fitting to an existing home may mean running pipes through walls; needs a sturdy roof with sun most of the day3 |
- ENERGY STAR says a certified solar water heating system can cut annual hot water costs in half, and is generally designed to work with a back-up heater3. Actual savings depend on use, location and tariff.
- It advises installing heat pump water heaters in interior spaces that stay between about 4 and 32°C (40–90°F) year-round, with at least about 28 m³ (1,000 cubic feet) of air2. In very hot places such as unconditioned roof rooms, check the model's operating limits in the manufacturer's data.
Practical advice: choose capacity by the number of people and peak demand (several showers in a row), and ask the supplier for the manufacturer's capacity table rather than a verbal "estimate". Keep hot water pipe runs as short as possible.
Energy efficiency label: mandatory in Saudi Arabia
- Water heaters are on the list of products with a decision to apply energy efficiency requirements under the General Technical Regulation for Energy Efficiency, with standard SASO 28844.
- The regulation prohibits manufacturing or importing non-conforming products, and placing, offering or advertising them on the market unless they carry the label4.
- The label licence is tied to the model; any change to the product (other than cosmetic, such as colour) cancels the licence and requires a new application4.
Legionella: why temperature matters
Legionella is a bacterium living in water systems that can cause serious pneumonia (Legionnaires' disease) when contaminated water droplets are inhaled. The UK Health and Safety Executive (HSE) explains that the bacteria multiply between 20–45°C, are dormant below 20°C, and do not survive above 60°C5. The US Centers for Disease Control and Prevention (CDC) also provides tools for managing the risk in building water systems6.
Recommended temperatures
| Part of the system | Recommended temperature (HSE) |
|---|---|
| Hot water storage in the heater/cylinder | 60°C or above |
| Hot water distribution | 50°C or above |
| Cold water storage and distribution | below 20°C |
Source: HSE guidance on managing Legionella in hot and cold water systems5.
Preventing scalds
Water at 60°C can cause burns, especially to children and older people. The solution isn't lowering the heater temperature but controlling temperature at the point of use: HSE recommends fitting thermostatic mixing valves as close as possible to outlets where there is a scalding risk5.
Practical steps at home
- Set the heater thermostat so water is stored at about 60°C.
- Fit thermostatic mixers in showers, especially with children or older people at home.
- Run rarely used taps regularly, and remove unused branches when renovating.
- Clean and descale showerheads periodically.
- Check the heater's safety valve works and discharges to a safe place.
- Use pipes suitable for the thermal application class; see the pipe types guide.
This information is for awareness. Public buildings and healthcare facilities have specialised water management plans and regulatory obligations.
Sources
The number next to a statement points to its source in this list. Sources back the general information; anything marked “practical advice” is editorial experience, not a quoted source. Anything that affects safety, structural design or electrical installations needs a licensed professional, and in Saudi Arabia the binding reference is the Saudi Building Code.
- 1High Efficiency Electric Storage Water Heaters — How It Works — ENERGY STAR (U.S. EPA / DOE)
- 2Heat Pump Water Heaters — ENERGY STAR (U.S. EPA / DOE)
- 3Solar Water Heaters — ENERGY STAR (U.S. EPA / DOE)
- 4General Technical Regulation for Energy Efficiency (Amendment 3, 2023) — Annex 1 product list incl. water heaters, SASO 2884 — Saudi Standards, Metrology and Quality Organization (SASO)
- 5Managing legionella in hot and cold water systems — Health and Safety Executive (HSE)
- 6Controlling Legionella in Potable Water Systems — Centers for Disease Control and Prevention (CDC)