Regulation 31 does not apply to every construction business. However, it can be highly relevant to contractors whose work affects the products, materials or chemicals used within public drinking water systems.

That influence goes beyond physically installing a pipe. Decisions made during design, specification, procurement, installation and maintenance can all determine whether a product is suitable and used correctly.

For contractors working on drinking water infrastructure, understanding Regulation 31 can therefore be an important part of protecting water quality, meeting client requirements and reducing compliance risk.

Who Does Regulation 31 Apply To?

Regulation 31 is particularly relevant to organisations involved in the specification, procurement, installation, maintenance or use of products that come into contact with drinking water.

This could include:

• Civil engineering contractors
• Water and utilities contractors
• Developers, self-lay organisations and developer services teams
• Mechanical, pipework and pipeline contractors
• Product manufacturers, suppliers and distributors
• Designers, consultants and procurement teams
• Capital delivery, operations and maintenance contractors
• Supervisors and managers responsible for checking compliance

The key question is not simply, “Are we a construction contractor?” It is: Could our work influence which products enter a drinking water system or how those products are used?

If the answer is yes, Regulation 31 awareness may be relevant to the organisation and the people making or implementing those decisions.

What Is Regulation 31 for Drinking Water?

Regulation 31 of the Water Supply (Water Quality) Regulations 2016, as amended, controls the substances and products used by water undertakers in the treatment and distribution of public drinking water in England.

The Drinking Water Inspectorate (DWI) explains that it covers chemicals and construction products used from the water source up to the point at which water is delivered to the consumer’s building. Its purpose is to ensure those products do not adversely affect water quality or consumer safety.

The legal wording is principally directed at water companies. However, water companies depend on contractors, consultants, designers and suppliers to select and use compliant products. Requirements can therefore flow through project specifications, procurement procedures, contracts, approved-product controls and site instructions.

Wales has corresponding requirements under the Water Supply (Water Quality) Regulations 2018. Equivalent provisions appear under Regulation 33 in Scotland and Northern Ireland. Businesses working across the UK should check the requirements applying to the relevant region, asset owner and project.

The Drinking Water Inspectorate’s Regulation 31 guidance provides the authoritative starting point for England and Wales.

Which Products Need Regulation 31 Approval?

Regulation 31 can be relevant wherever a substance, material or component may come into contact with water intended for public supply. This could include pipes and fittings, valves, coatings, membranes, sealants, adhesives, repair materials, treatment equipment and water-treatment chemicals.

Contractors should not assume that a familiar product, a recognised standard or a general claim of suitability for potable water automatically satisfies the requirements of a particular project.

The DWI maintains a list of approved products for use in public water supplies. It notes that some construction-product standards cover general fitness for purpose without adequately demonstrating suitability for contact with drinking water.

Is Using a Regulation 31 Approved Product Enough?

Approval is only part of compliance. A product may have conditions governing where and how it can be used, including:

• Its approved purpose or application
• Surface-area limitations
• Preparation and installation methods
• Mixing, curing or drying times
• Flushing, disinfection or testing requirements
• Storage and record-keeping arrangements

An approved product can still create a risk if it is substituted without checking, installed incorrectly or brought into use before the required process has been completed.

When EUSR launched its Products for Drinking Water scheme in 2025, it highlighted a DWI investigation in which taste and odour problems were traced to a reservoir sealant that had not been used in accordance with the manufacturer’s guidance. A required taste and odour test had also been missed.

The lesson for contractors is straightforward: product approval, instructions for use and site controls must work together.

What Are Contractors Responsible for Under Regulation 31?

The controls required will depend on the project and the water company’s procedures. However, contractors may need to:

• Confirm approval requirements before purchasing or using a product
• Check current DWI and project-specific approved-product information
• Follow all instructions and conditions attached to the product
• Control product substitutions
• Ensure the relevant teams understand installation and commissioning requirements
• Keep appropriate product, batch and installation records
• Escalate uncertainty before a product is used

This should not be left entirely to the installer. Designers, buyers, project managers and supervisors may all influence whether the correct product reaches the correct part of the system and is used under the correct conditions.

Products for Drinking Water vs National Water Hygiene: What Is the Difference?

Both EUSR schemes support safe drinking water, but they address different risks.

The courses are not interchangeable. Depending on the role and the water company’s requirements, a contractor may need one registration, both or additional training.

Someone entering a restricted clean-water site may need EUSR National Water Hygiene training. Someone who specifies, procures, approves, installs or manages products used within a drinking water system may also need Products for Drinking Water.

Who Needs EUSR Products for Drinking Water Training?

Launched in 2025, the EUSR Products for Drinking Water scheme was developed with UK water companies and key water-industry stakeholders. It helps operatives, supervisors, managers and professionals understand the relevant regulations and their responsibilities within the drinking water supply chain.

The course covers the scope of the regulations, approved-product lists, instructions for use, water-treatment chemicals, compliance risks and record keeping.

Essential Site Skills delivers the EUSR Products for Drinking Water course as a half-day, face-to-face programme. Delegates complete a 25-question multiple-choice assessment, with successful completion leading to an EUSR registration valid for three years.

Training supports awareness and competence, but it does not replace product-specific instructions, project procedures or specialist regulatory advice.

Does Regulation 31 Apply to Your Organisation?

A general building contractor with no involvement in public drinking water infrastructure is unlikely to face the same requirements as a civil engineering business installing pipework, applying reservoir coatings or managing materials for a water-company project.

However, it is worth reviewing roles and training needs if your organisation:

• Works for or on behalf of a water company
• Delivers drinking water treatment, storage or distribution projects
• Carries out developer services or self-lay work
• Specifies or procures products for clean-water assets
• Installs, repairs or maintains components that contact drinking water
• Supplies products or technical advice to the drinking water sector

The review should include everyone who influences product selection and use, not just those carrying out the physical installation.

The EUSR Products for Drinking Water course can help your team better understand approved products, instructions for use and its role in protecting drinking water quality.

To discuss course availability or arrange training for your organisation, call Essential Site Skills on 0115 8970 529 or make an enquiry through the course page.