Natural and Traditional Products (Advice Sheet 10)

Glossary

Version 1.6  October 2025

1. Introduction

Under the Water Supply (Water Quality) Regulations 1989, most traditional substances, including those based upon natural ingredients, used with water intended for human consumption (drinking water) came under the requirements of either regulation 25(1)(c) or 25 (1)(d)

1.1 Traditional Products

These include substances and products that have been used in the past under the requirements of regulation 25 (1)(c or d)^[1] in the collection, treatment and/or distribution of public water supplies, e.g. bitumen lined ductile iron pipes, or flexible rising mains for use in bore-holes. For further guidance and help see Section 3 of this Advice Sheet.

1.2 Natural Substances and Ingredients

These include:

• a whole product (or the major component of a product), of natural origin, used in contact with water intended for human consumption, perhaps as part of water treatment, e.g. barley straw used for algal control in reservoirs, or tannin used in coagulants and flocculants
• an ingredient or component of another product, e.g. asphaltic bitumen used in semi-porous coatings for the water contact surfaces of cement mortar lined ductile iron pipes (see FAQ 9)

1.3 The Current Regulations

Under the current regulations the “grandfather rights” previously in place through regulation 25 (1)(c) and (d) were no longer available and such natural and traditional products are now subject to formal application for approval under Regulation 31 of the current Regulations – see Advice Sheet 1 for an overview of the requirements.

The following sections review of issues of concern and the approach now adopted to the approval of such products and ingredients.

2. Issues of Concern

2.1 General

When considering these natural and traditional products and ingredients, the same basic assumptions have to be made that are used in the evaluation of new products for approval under regulation 31 of the current Water Supply (Water Quality) Regulations. These products are evaluated taking into account issues such as:

• the exposure of the product or ingredient to water intended for human consumption (both contact surface area to volume, and contact duration), and whether they fall under the requirements or regulation 31(4)(a) or 31(4)(b); for further advice refer to Advice Sheet 8
• the degree of control that could be achieved over the quality and variability of a natural ingredient used in the product
• for products falling under the requirements of regulation 31(4)(a), the potential toxicity of compounds leaching into water from the product, based upon declaration of ingredients and or results of leachate studies, e.g. pesticides and/or herbicides, or compounds such as polycyclic aromatic hydrocarbons (PAHs)
• the potential (anticipated) overall risk to public health through drinking the water on contact with the product

2.2 Maintenance and Replacement Parts

There has been concern about continued use of some products by water undertakers on the basis of their past use, without problems; i.e. like-for-like replacement of traditional products that have been in use over many years. The Inspectorate has agreed that such a like-for-like replacement strategy is not acceptable unless the replacement has met the appropriate requirements of regulation 31 of the Water Supply (Water Quality) Regulations 2016, with the following exceptions:

1. bespoke plant items previously approved under regulation 25 of the Water Supply (Water Quality) Regulation 1989 and held in storage for future use in order to maintain the plant
2. service replacement low contact parts (small contact surface area or transient contact time, i.e. falling under the requirements of regulation 31(4)(b)) for obsolescent or obsolete products and plant previously approved under regulation 25, that are no longer available from the original manufacturer and/or supplier, and have not been assessed under regulation 31. For further guidance refer to Advice Sheet 8 and/or seek advice from the Inspectorate.

In both of these latter cases the use of these service or maintenance parts is permitted provided the water undertaker carries out a risk assessment to satisfy themselves of the continued fitness for purpose and safety of the component(s) for use in public water supplies. In all other cases full conformity with the appropriate requirements of regulation 31 of the current Regulations is required.

2.3 Examples

Some examples of the approach that has been taken with both traditional products and natural ingredients are given in Section 4 below.

3. Applications for Approval: Requirements

In the main these are the same as those given in Advice Sheet 1 together with the appropriate requirements for the Instruction for Use document(s) given in Advice Sheet 2. Applications should be made via the online portal.

In the case of natural ingredients additional information is required as part of the application documentation, including details of:

1. Source(s) of the natural ingredients or components
2. The natural variability of the chemical makeup and nature of the ingredient (component)
3. The analytical controls in place to ensure consistency of the ingredient (component)
4. Analytical results from testing of the product during a minimum period of three months, demonstrating conformity with the requirements
5. Potential interaction between the ingredient (component) or leachates from it, with chlorine in water, or in the case where contact is limited to un-treated water, the potential of leachates to react with chlorine later in the treatment process
6. For ingredients or products based upon plants and extracts from them, what controls are in place over herbicides and pesticides use during their growth, harvest and subsequent storage of them.

4. Examples: Specific Products/Ingredients

The following examples highlight how these concerns have been applied to various product types, in evaluating whether:

• approval under regulation 31(4)(a) is relevant and/or possible
• the control of the consistency of the appropriate natural ingredient(s) could be achieved
• the degree of risk posed by the proposed use

a. Asphaltic bitumen – here the concern has been the potential degree of variability of the bitumen, and its potential leachates, arising out of the different open-market source of the bitumen used as the major ingredient (plus suitable solvents) to make bitumen based coatings and enamels. Interested manufacturers and suppliers of bitumen containing products to make a formal submission of their products for evaluation in a trace organic analysis of leachates by GC-MS general scan. Due to the low commercial margins associated with these products, no manufacturer has yet submitted any bitumen based product for formal evaluation under these requirements.

b. Flexible rising mains for boreholes – Full approval required under Regulation 31 (4)(a), already approved products can be found in section B.2 of the List

c. Vegetable oils (e.g. castor oil) – used as an ingredient in some coatings. The Inspectorate has been advised to accept such ingredient without further specific test requirements for the ingredient, provided that they are of known quality, e.g. food or pharmaceutical grade and tested to demonstrate compliance with the appropriate requirements. Such acceptance does not cover, however, the normal testing requirements associated with the approval of any product under regulation 31(4)(a).

d. Natural substances used in water treatment processes – here the approach adopted has been to seek evidence of adequate quality control of the substance, including:

• substantive records of relevant analysis of manufactured batches of the product or ingredient over several months,
• details of chemical agents used to control pests and diseases during growth
• evidence of the efficacy of the product and the effects on water quality after treatment, including presence of leachates from the substance

To date satisfactory evidence has not been supplied for any such product to enable approval to be given.

e. Barley straw used for algal control – this has been accepted, provided that it had been grown without the use of pesticides, herbicides and related products.

1. Or the Fifteenth Statement of the committee on chemicals and materials of construction for use in public water supply and swimming pools, dated March 1989, Department of the Environment. ↑