Reservoir Refurbishment

Total specialist maintenance specialises in the refurbishment of potable water retaining structures on a national basis.

Total specialist maintenance provides Specialist repairs to potable water retaining structures. Repairs to structures are carried out during planned and emergency outages with a return to service times being critical to ensure that the water companies’ interruption to service is minimised.


Total Specialist maintenance carry out maintenance to the following structures

  • Underground reservoirs
  • Water towers
  • Braithwaite tanks
  • Contact tanks

All repairs carried out to potable water structures are carried out using DWI approved products to ensure that the DWI regulation 31 is maintained, and there is no risk of contamination to supply.



Concrete Repairs

Waterproof Containment Linings

Waterproofing to reservoir roofs

Including excavation of topsoil, loose-laid waterproof membranes, UV resistant liquid-applied waterproof membranes

Replacement of metal works

Replacement of ladders, pipework internal handrails, replacement of access hatches


Application of sealants hypalon bandage systems

Preparation and coating of existing pipe works

Blasting and coating of internal pipework

Cleaning and Chlorination



Directly Employed Workforce

Highly Skilled and Experienced Operatives

Certified Training


Accreditations: CHAS
Accreditations: Achilles
Accreditations: Safe Contractor
Accreditations: Constructionline

Ask Questions

Technical Questions About
Reservoir Refurbishment

Frequently asked questions about Total Specialist Maintenance reservoir refurbishment, for the Water industry and infrastructure sectors and technical queries regarding reservoir refurbishment

For any additional information that is not listed please contact our technical team

Regulation 31 of The Water Supply (Water Quality) Regulations 2016 (as amended)1 implements Article 10 of the Council of the European Union Drinking Water Directive (DWD) in England and Wales for all chemicals and construction products used by water undertakers, from the source of the water, up to the point of delivery to the consumer’s building. It sets out how approvals can be given to such construction products and materials that do not prejudice water quality and consumer safety.


From time to time the Drinking Water Inspectorate (DWI) receives requests for advice from manufacturers and suppliers of tanks, pumps and associated pipework, who have been told by plant designers, civil engineers, or even by Water Supplier’s staff that these products must conform to the requirements of relevant regulations . The test methods used to evaluate the suitability of materials and products for use with drinking water (BS 6920/WRAS tests of effect on water quality, and the leachate studies specified by DWI) are not designed for use with materials and products in contact with treatment chemicals.

Products covered by the regulations

In addition to chemicals that may be used in the treatment of drinking water supplies, the relevant regulations cover construction products which may be introduced into contact with water. Products which are introduced into contact with drinking water need to conform with the appropriate requirements of relevant regulations, and these products may, of course, also come into contact with treatment chemicals. Some tanks, pumps and associated pipework etc. may, however, never be introduced into contact with water and will only be used in contact with the appropriate treatment chemical(s). In this case approval under the relevant regulations is not given and DWI does not consider these products.

Fitness for purpose

DWI will assume that the users of any products that will be in contact with treatment chemicals will, nevertheless, have satisfied themselves about the compatibility/fitness of the materials of construction for use with the chemicals in question.


  • such products will not be considered by the DWI unless they will also be used with drinking water
  • the normal test requirements (under the relevant regulations) are not necessarily applicable or suitable for use with products in contact with treatment chemicals only
  • users of such products have the right to satisfy themselves that the materials used to make these products will be compatible with the treatment chemicals that will be in contact with them – this might involve testing, but any such testing is outside the remit of the relevant regulations and we are unable to comment upon any tests requested by users


Under normal circumstances ALL products approved under Regulation 31(4)(a) are listed in the “List of Approved Products for use in Public Water Supply in the United Kingdom” (the “List”) –Approved & Considered Products – Drinking Water Inspectorate ( Although this list is updated on a regular “need” basis throughout the year, it may take several weeks before an approved product is added to the list on the website; final approval is not confirmed until the applicant has formally accepted the conditions of approval.

You should normally assume that if there is no mention of the product in the “List”, then this product is not currently approved under Regulation 31(4)(a).

If you are unable to trace any reference to the product in the “List”, in the first instance you should ask the supplier of the product for a copy of the approval letter issued by ourselves. You should note, however, that this alone does not confirm final approval; this is withheld until the applicant formally accepts the full approval conditions. The date of this letter will determine the next step that you should take:
  1. If this letter is dated up to 6 months before the date of the current “List” on our website, you should check with us as to when the final approval is likely to be confirmed on our website. To enable us to help you with this it is vital that you provide the name of the product, together with that of its supplier, and the DWI reference number for the product (this will be in the format DWI 56.4.XXX) – this information is included in the approval letter.
  2. If this letter is dated more than 6 months before the date of the current “List” on our website, but the product is not in the current list it is likely that the approval has been withdrawn for a variety of possible reasons; please contact us with the information set out in “a” above.
  3. If the supplier of the product is unable to provide you with an approval letter and/or DWI 56.4.XXX reference number, it is possible that the product has
    • never been approved or
    • former approval has been withdrawn/revoked or
    • it has been submitted for approval , but this has been subsequently withheld or refused. In this case contact us providing us with the name of the product, together with that of its supplier, and the DWI reference number for the product (see “a” above).

Products that can be approved

Only products that are used by or will be used by drinking water suppliers in the United Kingdom – from the source, through treatment, to the point of supply to consumers’ premises – can be approved under the relevant regulations. What types of products can be approved?
  • Treatment chemicals: Flocculants and coagulants, disinfectants, not covered by BS EN (products for use in building water systems cannot be considered)
  • Treatment process products: Adsorbents, ion exchange resins, membranes, on-site chlorine generators, filter media, vessels and containers, electrodialysis water treatment units, pressure vessels, products used for the physical treatment of water.
  • Pipes and associated components including coatings: Polyethylene (PE) (including barrier and laminated), polyvinylchloride (PVC), acrylonitrile-butadiene-styrene copolymer (ABS), polyethylene terephthalate (PET), glass reinforced plastic (GRP), stainless steel, and lined metallic pipes.
  • Site applied and in-situ coatings: coatings based on epoxy or polyurethane resins.
  • Repair materials
  • Water retaining structures
  • Covers and linings
  • Underdrains
  • Products for emergency use with public water supplies
The current list of approved products can be found on our website Some products are covered under relevant European standards and cannot be considered for approval:
  • Chemical products used for the treatment of water, are based solely upon a treatment chemical covered by a relevant BS EN standard
  • Inorganic supporting and filtering materials used for the treatment of water intended for human consumption, covered by relevant BS EN standards

Building water systems

Products used on customers’ premises, and in public buildings are covered by different approval requirements and regulations  The Water Supply (Water Fittings) Regulations 1999 (, and cannot be approved under Regulation 31 of the Water Supply (Water Quality) Regulations. For a comprehensive explanation, including the role of the Water Regulations Advisory Scheme (WRAS), see Annex 1 below.

Swimming Pool water treatment

Although a voluntary non-regulatory approval scheme for swimming pool chemicals was operated by the former Department of the Environment, Transport and the Regions (DETR) until 1999, this scheme was abandoned for a number of reasons, including:
  • DETR never had operational or policy responsibilities for swimming pools and no other Department wanted to accept this responsibility
  • Chemical suppliers were reluctant to agree to an audit scheme to check the ongoing quality of the products approved under the voluntary scheme
  • There were concerns about potential product liability issues if someone suffered ill-health as a result of using an approved product
DETR sought to replace the voluntary scheme by a programme for the development of European Standards for swimming pool chemicals. Details of these standards are available from the British Standards Institution – DWI and DEFRA do not publish lists of swimming pool treatment chemicals. GENERAL NOTE: the Drinking Water Inspectorate is unable to comment on:
  • the suitability for use within building water systems or in the treatment of swimming pool waters, of any product approved under Regulation 31 of the Water Supply (Water quality) Regulations, including their fitness for purpose
  • the use of any other treatment chemical, product/device or process within building water systems or in the treatment of swimming pool waters
All such enquiries should be made directly to:
  1. Water Regs UK Limited for building water systems
  2. PWTAG | The home of the Pool Water Treatment Advisory Group (PWTAG) for swimming pool waters

The Water Regulations Advisory Scheme (WRAS)

This Scheme is operated behalf of the UK water industry by WRAS Ltd. The Scheme approves water fittings and materials, for use within consumers’ premises, to the requirements of the Water Supply (Water Fittings) Regulations 1999. For most non-metallic materials test methods and acceptance criteria for potential effects on water quality are specified in BS 6920[1].These tests include odour and flavour, appearance, growth of aquatic microorganisms, leaching of metals, and cytotoxicity. The scheme normally only accepts test reports from laboratories that have been accredited (under EN ISO/IEC 17025) for BS 6920 testing by the United Kingdom Accreditation Service (UKAS). Materials which meet the full test requirements of BS 6920:1 can be listed in the materials section of the Water Regulations Approval Scheme Ltd – Approvals Directory ( . In many cases WRAS will accept the use of listed materials in fittings without the need for any further testing, although mechanical testing of the fitting may be required. WRAS is concerned primarily with products used in BUILDINGS (CONSUMERS’ PREMISES) – the requirements of the Water Supply (Water Fittings) Regulations 1999 apply. [1] BS 6920 – Suitability of non-metallic products for use in contact with water intended for human consumption with regard to their effect on the quality of water

Regulation 31 Approval Scheme

The Drinking Water Inspectorate (DWI) operates the approval system for products used by UK water suppliersunder the requirements of the relevant regulations on behalf of the national authorities . DWI can accept applications for approval of products used both before and at the treatment works and in water distribution systems up to the point of delivery to premises. The only products considered for approval under Regulation 31 are those sold to water undertakers in the United Kingdom for use with water intended for human consumption. When considering non-metallic products for approval under the relevant regulations, however, the DWI does take into account the results of BS 6920 testing undertaken as part of the approval process for products listed by WRAS. Where products have not been previously tested to BS 6920 and/or listed by WRAS, a normal requirements for approval will include satisfactory results in the BS 6920 tests – see Section 4.2 of our Advice Sheet 1 for further details. Products recommended for approval under Regulation 31 are listed in the Approved & Considered Products – Drinking Water Inspectorate ( DWI does not approve any product for use with drinking water – [ link to FAQ2] The DWI only considers products (treatment chemicals and construction products) used in the PUBLIC WATER SUPPLY, i.e. between the point of source of water and the point of supply to consumers’ premises.

Table of Comparison

The following table summarises the differences between WRAS approvals and those given under Regulation 31 Table to compare the differences between WRA approvals and those given under Regulation 31
Within buildings (WRAS) In drinking water supply
Building water systems – consumer’s premises From source to consumer’s premises (including treatment works)
Individual materials Final products, including pipes, fittings and assembled products etc Treatment chemicals Final products, including treatment plant, pipes, fittings and assembled products
Legal basis – the Water Supply (Water Fittings) Regulations 1999 Legal basis – the relevant regulations
Testing to Parts 1 to 3 of BS 6920 Testing to Parts 1 to 4 of BS 6920, plus additional tests specified on a case-by-case basis
Direct effects on water quality – odour and flavour, colour and turbidity, microbial growth, leaching of metals Direct effects on water quality – odour and flavour, colour and turbidity, microbial growth, leaching of metals Health risks, usually associated with organic compounds leaching from the product