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Brochures
Assumptions
Our water savings calculator is designed to be informational and educational and the cost predictions and savings are illustrative of what you could incur annually. We have made the following assumtions about usage.
Actual costs and savings may vary from household to household depending on a number of factors, so although every effort has been made to provide an accurate depiction of the potential savings, Methven UK accepts no liability with regards to the level of savings that are actually achieved.
Energy Cost (per kWh)
£0.05740
Source: Ofgem domestic energy price-cap gas unit rates (1 April–30 June 2026), average Direct Debit rate including VAT.
Water Cost (per litre)
£0.00395
Based on Ofwat average household water and sewerage charges (2026–2027) using typical metered tariffs across England and Wales.
- Water + sewerage: £3.9525 per m³
- Cost per litre: £0.00395
Sources:
Ofwat average household bills 2026–2027
UK water company tariff data (2026–2027)
Flow Rates
The water savings calculator compares the selected handset flow rate against an average UK shower flow rate of 15 litres per minute (l/min).
- Developer Part G calculations compare a standard 15 l/min handset with the Kiri Low Flow handset (5.5 l/min).
- Homeowner calculations compare a standard 15 l/min handset with the Aurajet Aio handset (8 l/min).
- Shower heads are tested at a working pressure of 3.0 bar.
Energy Usage
Hot water is assumed to be supplied by an A-rated gas combi boiler. Boiler efficiency reflects typical modern UK combi boilers and assumes well-insulated pipework between the boiler and shower.
Boiler efficiency: 85% (typical range 70–92%)
Gas Cost Estimate
Based on Ofgem domestic energy price-cap average UK gas unit rates (1 April–30 June 2026).
Gas unit rate: £0.05740 per kWh
Source: Ofgem energy price cap and typical UK household unit rates
Water Cost Estimate
Based on Ofwat UK average household water and sewerage charges (2026–2027) using typical metered tariffs across England and Wales.
- Water + sewerage: £3.9525 per m³
- Cost per litre: £0.00395
Sources:
- Ofwat average household bills 2026–2027
- https://www.ofwat.gov.uk
- UK water company tariff data (2026–2027)
Carbon Footprint
Relevant emissions factors for natural gas heating:
CO₂e per kWh of heat from a gas boiler: 0.21 kg
Source: UK Government / DESNZ emissions factors and industry data.
Energy Savings Calculation Assumptions
Assumptions have been made about typical UK shower usage:
- Shower outlet temperature: 40 °C
- Cold inlet temperature: 10 °C
- Hot inlet temperature: 60 °C
- Energy required to heat 1 litre from 10 °C to 60 °C: 209,300 J
Average UK household occupancy: 2.36 people
Source: ONS Census data
- Average shower duration: 11 minutes
Source: Bathroom Association 2023 research
Most UK homeowners shower at least once per day.
