What is a Waste Water Heat Recovery system?

Waste Water Heat Recovery used in outdoor shower head for the bath and showering cold water to body before jumping in the resort pool
Waste Water Heat Recovery uses hot water that would otherwise be washed down the drain (Image credit: Getty Images)

A Waste Water Heat Recovery system, also known as a drain water heat recovery system, is designed to capture and reuse the heat energy from hot water that is typically discarded down the drain. 

This type of system is employed to improve a home's energy efficiency and could be required for all new homes by 2025 due to the Future Homes Standard.

In anticipation of this regulation change, we take you through how this system works, how it compares to other systems, how much it will cost and how it can help you combat energy price rises.

How does a Waste Water Heat Recovery system work?

A Waste Water Heat Recovery system captures and reuses heat from hot water that would otherwise be lost down the drain. 

It involves installing a heat exchanger in the drainpipe, which captures heat from used hot water. This captured heat is then transferred to the cold water supply, preheating it before entering the water heating system. 

The system improves overall energy efficiency, helps with water bills and reduces environmental impact by reusing heat that would otherwise be wasted. 

The effectiveness of the system can vary based on factors such as the heat exchanger design and local conditions.

What are the benefits of a Waste Water Heat Recovery system?

energy performance certificate

A Waste Water Heat Recovery system can help improve your homes EPC rating and help it meet building regulations (Image credit: Getty)

A Waste Water Heat Recovery system offers various advantages, including enhanced energy efficiency and cost savings by capturing and reusing heat from wastewater. 

David Hilton, Homebuilding & Renovating's expert in sustainable buildings and energy efficiency, states: "The system reduces environmental impact and conserves resources by reducing greenhouse gas emissions associated with water heating."

Despite a high upfront cost, the long-term benefits make it a sustainable and cost-effective investment saving up to 450-500kWh per person per year - around £20 per person, according to installers The Code Store.

Waste Water Heat Recovery is acknowledged by SAP calculations (Standard Assessment Procedure) as an energy-saving technology, assisting house builders in meeting Building Regulations Part L.

A Waste Water Heat Recovery system will therefore help your home comply with Building Regulations, especially as new homes potentially being required to use the system by 2025 due to the Future Homes Standard.

David Hilton
David Hilton

With more than 35 years of expertise, David is a seasoned renewables and ventilation installer, recognised for his longstanding contributions to Homebuilding and Renovating magazine. Holding membership in the Gas Safe Register and armed with a Masters degree in Sustainable Architecture, David stands as an authoritative figure in sustainable building and energy efficiency. His extensive knowledge spans building fabrics, heat recovery ventilation, renewables, and conventional heating systems. Additionally, he serves as a distinguished speaker at the Homebuilding & Renovating Show.

How much do they cost to install?

According to energy saving advice portal The Greenage installation of Waste Water Heat Recovery systems cost around £1,000 for new homes.

However, for existing homes this fee is expected to be higher with the amount depending on the existing pipework in the home.

How do they compare to other systems?

Solar PV panels on a roof

Waste Water Heat Recovery systems can prove to be more cost-effective for reducing hot water costs than solar panels in some contexts (Image credit: Future/David Hilton)

Waste Water Heat Recovery systems stand out as a cost-effective and efficient technology for enhancing a building's energy performance, recognised by SAP.

Compared to other renewable energy systems like solar panels and air source heat pumps, Waste Water Heat Recovery systems excel in certain contexts when it comes to cost-effectiveness, space efficiency (taking up no floorspace), and suitability for regular hot water usage. 

However, the choice between these systems depends on factors such as building characteristics, local climate, and specific energy needs.

Joseph Mullane
News Editor

News Editor Joseph has previously written for Today’s Media and Chambers & Partners, focusing on news for conveyancers and industry professionals.  Joseph has just started his own self build project, building his own home on his family’s farm with planning permission for a timber frame, three-bedroom house in a one-acre field. The foundation work has already begun and he hopes to have the home built in the next year. Prior to this he renovated his family's home as well as doing several DIY projects, including installing a shower, building sheds, and livestock fences and shelters for the farm’s animals. Outside of homebuilding, Joseph loves rugby and has written for Rugby World, the world’s largest rugby magazine.