In the light of the Government’s consultation on proposed changes to Part G (Water Efficiency) of the Building Regulations, the Future Homes Hub recently brought together developers, technical specialists and partners for a constructive and wide-ranging discussion on the recommended steps and pathway to future water efficiency standards. The session: 

• Reviewed the consultation and sought views on the deliverability of the proposals.
• Considered the proposals’ implications for the Water Ready report’s recommended roadmap for increased water efficiency standards and the actions needed to help achieve these.
• Reviewed the call for evidence questions in the consultation. 

In the course of a wide-ranging and constructive discussion, attendees also discussed what a practical, future-ready regulatory regime could look like and what the sector needs to ensure any transition is workable, innovation-friendly and aligned with wider environmental goals. 

A Shift Toward Fittings-Based Standards 

The Water Ready report recommended a fittings-based approach for future Part G standards, but it also stated that for the immediate future at least there remained a case for retaining a water calculator. The consultation recognises the argument for retaining a calculator at present, but it also signals a direction of travel of moving Part G toward a fittings-based approach linked to the forthcoming Mandatory Water Efficiency Labelling Scheme (MWELS).  

Members saw the merits of such a regime but stressed that a successful transition would need a staged, practical pathway. Developers - especially SMEs - must be able to demonstrate compliance with both new Part G requirements and more ambitious local planning expectations where these exist. A revised water calculator was therefore seen as essential during the transition. 

The Water Calculator: A Priority for Change 

The retention of a water calculator was recommended in the Water Ready report, with the proviso that the current calculator required revision to be more accurate and take account of changes since its introduction. The group built on this conclusion in its discussion of the changes to the calculator proposed in the Part G consultation. Issues raised included: 

• Outdated default values for white goods make it harder for developers to meet tighter standards, as they don’t reflect modern, efficient appliances. 
• Setting minimum flow rates for fittings such as showers and toilets could discourage innovation: customer experience should be a guiding consideration. 
• The proposed removal of the normalisation factor could make meeting new standards unnecessarily difficult.
• A revised calculator should better support innovation, enabling developers to demonstrate the benefits of new technologies or design approaches.
• Energy and carbon impacts of fittings must be considered, so that, where possible, water-efficient specifications don’t inadvertently undermine energy performance.
• Variations in water pressure across areas and regions need to be factored into any calculation methodology. 

The Hub offered to support government in advising on a practical revision of the tool. 

The Level of Future Standards 

The proposed revised Part G standards of 105 and 100 litres per person per day are in line with the Water Ready report’s recommendations for 2025. It was noted that requirements beyond these levels could pose challenges, particularly for SMEs. The future further tightening of Part G standards was proposed in Water Ready, but the report recognised that the achievement of tighter standards would require a collaborative approach between government, the water industry, home builders, the supply chain and others to agree and implement a series of necessary enabling actions. 

Members agreed that the debate on future standards is best framed around fittings-based performance, not litres-based calculations alone. . 

Water Reuse and External Water Use 

In its Call for Evidence that accompanies the Part G consultation, the government has sought views on whether a requirement for water reuse systems should be included in future standards. The Water Ready report recognised that water reuse systems would be needed to help meet the more ambitious future standards envisaged under its roadmap, but the group noted the need for further exploration of potential regulatory pathways to achieve this. Key challenges to be addressed include water reuse in future Part G requirements, potentially introduced in stages (e.g., starting with larger developments). However, concerns were raised about: 

• Maintenance and adoption responsibilities for communal systems
• Cost implications and consumer acceptability
• The need to improve the current method for assessing external water use 

Building Control and Implementation 

Members noted ongoing challenges with building control capacity, particularly around inspection of water-related requirements. Better alignment with MWELS in future standards could help streamline compliance. 

Next Steps: Revisiting Water Ready 

As an overarching conclusion, the group agreed to revisit the Water Ready sector roadmap to set out, step by step, what needs to happen next, based on the sector’s experience to date. This will form an early task for the new Water Smart Growth Board, ensuring the sector has a clear, evidence-based pathway toward more efficient, resilient water use in new homes.