Building Regulations Part G: Complete Guide to Sanitation, Hot Water & Water Efficiency

What is Building Regulations Part G?

Building Regulations Part G is the part of the Building Regulations in England concerned with sanitation, hot water safety and the efficient use of water. The practical guidance used by designers, installers and Building Control is set out in Approved Document G.

In everyday terms, it is intended to make sure homes have safe and suitable water supplies, properly designed hot water systems, appropriate toilets and washing facilities, and suitable provision for bathrooms and food preparation.

Part G is only one part of the overall compliance picture. If you are planning an extension, conversion or renovation, our complete homeowner’s guide to the approval process explains how the different requirements fit together.

What does Building Regulations Part G cover?

Approved Document G divides the requirements into six main areas. Although they are closely related, each deals with a different part of water supply or sanitation.

• G1: cold water supply.
• G2: water efficiency.
• G3: hot water supply and hot water systems.
• G4: sanitary conveniences and hand-washing facilities.
• G5: bathrooms.
• G6: food preparation areas.

Approved Documents provide recognised guidance on ways of satisfying the regulations. However, they should not be treated simply as a design specification to copy without considering the individual project.

Building Regulations Part G1: cold water supply

G1 requires suitable water supplies to be provided for normal domestic uses. In particular, wholesome water is required at drinking-water outlets and food-preparation sinks, while suitable wholesome or softened wholesome water may be used for certain washing facilities.

The design also needs to consider contamination risk, backflow protection and the suitability of pipes, fittings and storage arrangements.

This is one reason plumbing design should not be considered separately from the wider Building Regulations package. Building Control may need sufficient information to understand how the proposed installation will operate.

Building Regulations Part G2: water efficiency

G2 is aimed at preventing unnecessary water consumption. For a new dwelling in England, the calculated consumption of wholesome water is normally limited to 125 litres per person per day.

In some developments, planning permission can impose the optional requirement of 110 litres per person per day. Where that condition applies, the design needs to achieve the lower figure.

How is Part G water efficiency checked?

Compliance can involve the approved water-efficiency calculation methodology, taking account of items such as:

• WC flush volumes;
• shower flow rates;
• bath capacity;
• basin and kitchen tap flow rates;
• dishwasher consumption; and
• washing machine consumption.

Building Regulations Part G3: hot water safety

G3 deals with both the provision of hot water and the safety of the hot water system itself. Systems must be designed and installed so that they can safely withstand the temperatures and pressures that can reasonably occur.

Particular care is required with hot water storage systems and their safety devices. Any discharge from safety devices must also be routed safely.

Part G3 and bath water temperature

A particularly important homeowner requirement concerns fixed baths. The hot water installation must incorporate measures so that water delivered to a fixed bath cannot exceed 48°C.

This is commonly achieved through appropriate temperature-control arrangements, such as a thermostatic mixing or blending valve.

Part G4, G5 and G6: sanitation, bathrooms and kitchens

G4 – sanitary conveniences and washing facilities

G4 requires adequate and suitable sanitary conveniences and hand-washing facilities. It also deals with the relationship between toilet accommodation and areas used for food preparation.

G5 – bathrooms

For dwellings and residential accommodation within its scope, G5 requires a bathroom containing a washbasin together with either a fixed bath or a shower.

Bathroom projects may also need to satisfy ventilation and electrical requirements. Our guide to ventilation requirements for homes explains the connection with extraction and airflow.

G6 – food preparation areas

G6 requires a suitable sink in an area where food is prepared. This is therefore particularly relevant when creating or relocating a kitchen as part of an extension or refurbishment.

When do homeowners need to consider Part G?

Part G frequently becomes relevant when a project changes water services, bathrooms, kitchens or hot water systems. Typical examples include:

• new-build homes;
• house extensions containing a kitchen, utility room, WC or bathroom;
• loft conversions with an en-suite;
• garage or basement conversions containing sanitary facilities;
• new or significantly altered bathrooms;
• relocated kitchens;
• installation or alteration of hot-water storage systems; and
• some material changes of use.

Whether a particular piece of work needs a Building Regulations application depends on the work being carried out. Our guide to preparing a Building Regulations application explains the usual routes.

Where detailed information is needed, properly prepared technical drawings for Building Control can help coordinate plumbing, drainage, structure, insulation and other requirements before construction begins.

Building Regulations Part G homeowner checklist

Before submitting drawings or starting work, use this simple checklist to make sure the main Part G issues have been considered.

Building Regulations Part G and other Approved Documents

A common mistake is to assume that one part of the regulations deals with the whole bathroom or kitchen. In reality, several requirements often overlap.

Part G and Part H

Part G concentrates on water supply, sanitation and hot-water safety. Drainage and wastewater disposal are covered separately. Our guide to drainage and waste requirements explains this distinction.

Part G and Part F

Bathrooms, WCs, utility rooms and kitchens also need suitable ventilation. Therefore, an apparently simple bathroom alteration may involve both water-services requirements and ventilation design.

More generally, it helps to understand how Approved Documents are used and how Building Control checks compliance before work begins.

FAQs: Building Regulations Part G

Next steps & useful guides

If you are planning work involving plumbing, bathrooms, kitchens or Building Control approval, these related PME guides will help you put Part G into context:

• Complete homeowner’s guide to compliance and approvals
• How Building Control works and what inspectors check
• How the Approved Documents are used
• How to prepare and submit an application
• What technical drawings normally need to show
• Drainage and waste requirements explained
• Ventilation requirements for homes explained

Official guidance and useful references

Regulations and guidance can change, so check the latest official sources before relying on technical requirements:

• GOV.UK – official sanitation, hot water safety and water-efficiency guidance
• UK legislation – The Building Regulations 2010
• Planning Portal – practical guidance on sanitation, hot water and water efficiency
• Water Regs UK – guidance on compliant water fittings

Getting Part G right before work starts

For most homeowners, Part G becomes important when a project introduces or changes a kitchen, bathroom, WC, shower, bath or hot-water system. The individual requirements are not especially difficult to understand, but they interact with drainage, ventilation, electrical safety and the wider Building Regulations.

Consequently, the easiest approach is usually to coordinate these points during the technical design stage rather than trying to correct them once construction is under way. Good drawings, appropriate product information and early discussion with Building Control can prevent avoidable changes on site.

Plans Made Easy can prepare compliant drawings, help coordinate the relevant Approved Document requirements and guide you through the Building Control process so you know what needs to be resolved before your builder starts.