Domestic Water Treatment Approval Scheme (DWTAS)

The longevity and efficiency of water heating primary circuits and boilers, including central heating systems, can be greatly improved by the use of chemical water treatment. The purpose of these treatment fluids in central heating systems is to:

·         inhibit corrosion of vital metallic parts such as pipes and radiators,

·         prevent scaling up of the system, and in particular the boiler.

In addition the fluid should not cause damage to plastic and rubber components of the system and should have a low environmental impact.

All chemical water treatment fluids certified by BuildCert are tested against standards drawn up by industry experts to ensure that they perform to the criteria above. BuildCert’s quality assurance requirements check that every bottle of water treatment fluid sold with its BuildCert DWTAS logo on it performs as well as the last. BuildCert DWTAS Approval allows boiler manufacturers, installers and consumers to have peace of mind that their hot water system is protected.

Water Treatment in the Building Regulations

In April 2006 the revised Building Regulations including “Approved Document L: Conservation of Fuel and Power” (England and Wales) was published.  In addition the ODPM published “Domestic Heating Compliance Guide” to help users interpret the Approved Document. These are available at

http://www.planningportal.gov.uk/england/professionals/en/4000000000562.html

http://www.communities.gov.uk/pub/340/DomesticHeatingComplianceGuide_id1165340.pdf

The Domestic Heating Compliance Guide specifically requires the use of chemical inhibitors both for new build heating systems and when a new heat source (boiler) is fitted to an existing heating system. The Guide also refers to BS 7593:2006 “Code of Practice for Treatment of Water in Domestic Hot Water Central Heating Systems”.

The Guide states: “Central heating systems should be thoroughly cleaned and flushed out before installing a new boiler.  During final filling of a system, a chemical treatment formulation should be added to the primary circuit to control corrosion and the formation of scale and sludge. Reasonable provision would be to follow the guidance on how to prepare and commission systems given in BS 7593.”

BuildCert

To ensure that chemical inhibitors meet a satisfactory performance requirement the manufacturers, BuildCert and laboratories developed the DWTA Industry Specification for the performance of Chemical Inhibitors for Use in Domestic Hot Water Central Heating Systems (February 2006).

The Specification was published in February 2006 and is now being used as a benchmark for chemical inhibitor manufacturers as a basis for developing chemical inhibitors and by BuildCert to offer 3rd party Certification.

For a copy of the Specification see (http://www.dwta.org.uk/default.asp).

Equipment manufacturers, installers and end users can now be sure that BuildCert approved chemical inhibitors will provide an effective resistance to corrosion within a heating system when correctly used.

Chemical inhibitors are tested in BuildCert approved laboratories who test the inhibitor against the exacting requirements of the BuildCert Domestic Water Treatment Approval Scheme (DWTAS) Specification for the performance of Chemical Inhibitors for Use in Domestic Hot Water Central Heating Systems.

To ensure that BuildCert Certified products are suitable for use, manufacturers are audited to verify that the contents of every bottle of product supplied are identical to the samples tested.

Manufacturers are then audited to ensure that every bottle of the product supplied is the same as the samples tested, ensuring that all BuildCert Certified products will be suitable for use.