Installing Pipework

If a premises has any form of mains water supply, then the water fittings regulations in England, Wales and Northern Ireland, byelaws in Scotland, apply. 

These legal requirements play an important role in protecting public health and safeguarding water supplies. Their purpose includes preventing the contamination and waste of water supplied by a water undertaker once it has entered a customer’s plumbing system. 

In addition to the restrictions on installation set out in regulation/byelaw 3 and requirements for water fittings specified in regulation/byelaw 4, schedule 2 includes a number of installation requirements, several of which are applicable when installing pipework.


Related FAQs

What is meant by an appropriate quality and standard?

<h1 id="what-is-a-water-fitting-of">What is a water fitting of an appropriate quality and standard?</h1><hr><figure class="img-responsive" style="float: right; margin-left: 20px; margin-right: 0px; width: 288px; min-width: auto; min-height: auto;"><img src="/images/topics/faqs/coverb-reg_4_1_a__compliance_guidance_april_2021_v1.1.png" class="img-responsive" style="width: 100%"></figure><p class="p1">To help prevent contamination and waste of mains water supplies the water fittings regulations in&nbsp;<a href="https://www.legislation.gov.uk/uksi/1999/1148/contents">England, Wales</a>&nbsp;and&nbsp;<a href="https://www.legislation.gov.uk/nisr/2009/255/contents/made">Northern Ireland</a>,&nbsp;<a href="https://www.scottishwater.co.uk/Help-and-Resources/Document-Hub/Business-and-Developers/Byelaws-and-Trade-Effluent">byelaws in Scotland</a>&nbsp;&nbsp;include specific requirements for water fittings. These include the legal requirement to be of an appropriate quality and standard for installation [regulation 4 (1)(a) &amp; 4(2)].</p><p class="p3">This regulation requires water fittings, and water using appliances, to either:</p><ul><li><p>Conform to an appropriate British Standard (or some other national specification which provides an equivalent level of protection and performance)</p></li></ul><p>Or</p><ul><li><p>Conform to a specification approved by the regulators</p></li></ul><p class="p1">If the water conveyed by these fittings needs to be wholesome – drinking water standard - any non-metallic materials or components within the fitting or appliance which comes into contact with water must also conform to the current version of&nbsp;<a href="https://knowledge.bsigroup.com/products/suitability-of-non-metallic-materials-and-products-for-use-in-contact-with-water-intended-for-human-consumption-with-regard-to-their-effect-on-the-quality-of-the-water-specification/standard">BS 6920</a>&nbsp;(or an equivalent).</p><p>Any questions please contact the local water undertaker for advice.</p><p><br></p><!--PARTBREAK--><h1 id="topics">FAQs</h1><!--PARTBREAK--><p><br></p>

What is meant by evidence of regulation 4(1)(a) compliance?

<h1 id="what-is-meant-by-evidence-of">What is meant by evidence of regulation 4(1)(a) compliance?</h1><hr><h4 class="p1" id="what-is-meant-by-evidence-of">&nbsp;</h4><figure class="img-responsive" style="float: right; margin-left: 15px; margin-right: 10px; width: 212px; min-width: auto; min-height: auto;"><img src="/images/topics/faqs/coverb-reg_4_1_a__compliance_guidance_april_2021_v1.1.png" class="img-responsive" style="width: 100%"></figure><p class="p1">This is evidence to show a water fitting is of an appropriate quality and standard for installation.&nbsp;</p><p class="p1">Water undertakers will consider evidence of compliance provided on a case and site specific basis.&nbsp;</p><p class="p1">Whilst this evidence must satisfy another regulation [4(2)], water undertakers have no preference for, or require it to be in a specific form. Typically, they will consider declarations of performance issued against designated standards, product certification and test reports. &nbsp;</p><p class="p1"><strong>Please note:&nbsp;</strong></p><ol><li><p>Because a water fitting must comply with all parts of the regulations being of an appropriate quality and standard does not, of itself, guarantee compliance with the regulations.&nbsp;</p></li><li><p>The latest available edition or version of guidance or specifications should always be used.&nbsp;</p></li><li><p>In respect of equivalence water undertaker retain absolute discretion in assessing whether a national specification provides an equivalent level of protection and performance to that specified in an appropriate British Standard. For information regarding the equivalence of a performance specification please contact your water undertaker.<br></p></li></ol><p class="p5">For further information please refer to&nbsp;<a href="/downloads/publications/booklets/reg_4__1__a__compliance_guidance_april_2025_v2.0.pdf">Regulation 4(1)(a) compliance guidance</a>&nbsp;and&nbsp;<a href="/downloads/publications/booklets/regulation_4_1__a__guidance_bs_6920_compliance_overview_april_2025_v2.0.pdf">BS 6920 Compliance Overview.</a></p><p class="p1">Any questions please contact the local water undertaker for advice.</p><p><br></p><!--PARTBREAK--><h1 id="topics">FAQs</h1><!--PARTBREAK--><p><br></p>

When does schedule 2 paragraph 2 not apply?

<h1 id="when-does-schedule-2-paragraph-2">When does schedule 2 paragraph 2 not apply?</h1><hr><h4 id="when-does-schedule-2-paragraph-2"></h4><p>Providing appropriate and adequate backflow protection against the highest level of risk downstream is installed, an installation not used to supply water for drinking, bathing, food preparation or cooking purposes is exempt from complying with schedule 2 paragraph 2(1). <br></p><p>Please note the backflow protection required needs to be assessed by the local water undertaker and other requirements of the water fittings regulations/byelaws continue to apply.</p><p>&nbsp;</p><p>&nbsp;</p><!--PARTBREAK--><h1 id="topics">FAQs</h1><!--PARTBREAK--><p><br></p>

What should be considered when designing a plumbing system?

<h1 id="what-should-be-considered-when-designing">What should be considered when designing a plumbing system?</h1><hr><p>When designing a compliant plumbing system a number of factors need to be considered, including but not limited to:</p><ul><li><p>Avoiding the risk of contamination or damage resulting from the environment in which the system is to be installed or due to the design itself.</p></li><li><p>The required and attainable supply pressure and other operational parameters</p></li><li><p>User expectations and whether these are achievable</p></li><li><p>Suitability of water fittings for use</p></li><li><p>Providing appropriate, adequate backflow protection.</p></li><li><p>Water efficiency</p></li><li><p>Limiting waste.</p></li></ul><p>Useful sources of information include <a href="https://knowledge.bsigroup.com/products/specifications-for-installations-inside-buildings-conveying-water-for-human-consumption-general/standard">BS EN 806 </a>and <a href="https://knowledge.bsigroup.com/products/guide-to-the-design-installation-testing-and-maintenance-of-services-supplying-water-for-domestic-use-within-buildings-and-their-curtilages-complementary-guidance-to-bs-en-807/tracked-changes">BS 8558</a></p><p>&nbsp;</p><p>&nbsp;</p><!--PARTBREAK--><h1 id="topics">FAQs</h1><!--PARTBREAK--><p><br></p>

What should be considered when selecting and installing pipework

<h1 id="what-should-be-considered-when-selecting">What should be considered when selecting and installing pipework</h1><hr><h4 id="what-should-be-considered-when-selecting"></h4><p>To help prevent waste and contamination all pipe and fittings systems must be of an appropriate quality and standard and suitable for the circumstances in which they will be used.</p><p>Before installing a pipe and fittings system key considerations will include but are not limited to:</p><ul><li><p>The compatibility of the pipe and fittings. For example, to ensure connections are watertight and configured to prevent galvanic action.</p></li><li><p>Whether the pipework is to be installed above or below ground</p></li><li><p>Where the pipework is to be installed. For example, in contaminated ground, in a duct and potentially exposed to construction materials and/or water vapour, somewhere exposed to sunlight or sources of heat.</p></li><li><p>What water temperatures and pressures the pipework will be exposed to. For example, hot or cold water only, heating systems, maximum operating pressure and thermal shock.</p></li><li><p>In the case of metallic water fittings, the possibility of corrosion due to galvanic action and dezincification.</p></li></ul><p>Useful sources of information include&nbsp;<a href="https://knowledge.bsigroup.com/products/specifications-for-installations-inside-buildings-conveying-water-for-human-consumption-general/standard">BS EN 806&nbsp;</a>and&nbsp;<a href="https://knowledge.bsigroup.com/products/guide-to-the-design-installation-testing-and-maintenance-of-services-supplying-water-for-domestic-use-within-buildings-and-their-curtilages-complementary-guidance-to-bs-en-807/tracked-changes">BS 8558</a></p><p>&nbsp;</p><p><strong>Please note:</strong></p><p>All water fittings should be resistant to corrosion. In the case of mechanical backflow prevention devices and metallic fittings which are not going to be readily accessible, in addition to being corrosion resistant these should be manufactured from materials which are not susceptible to dezincification. For example, gunmetal or CR brass.</p><p>As non-metallic pipe and fittings can be affected by sunlight and/or allow ingress of light, which is known to promote the growth of algae, consideration should be given to whether protective measures to exclude light are necessary.</p><p>Adhesive joints are not acceptable below ground.</p><p>&nbsp;</p><!--PARTBREAK--><h1 id="topics">FAQs</h1><!--PARTBREAK--><p><br></p>

Do water fittings have to be labelled?

<h1 id="do-water-fittings-have-to-be">Do water fittings have to be labelled?</h1><hr><figure class="img-responsive" style="float: right; margin-right: 10px; margin-left: 25px; width: 188px; min-width: auto; min-height: auto;"><img src="/images/topics/faqs/coverb-pipe_identification_bs_1710_1.4.21.png" class="img-responsive" style="width: 100%"></figure><h4 id="do-water-fittings-have-to-be"></h4><p>Irrespective of what fluid is being conveyed all pipework, whether installed above or below ground, should be marked in accordance with the latest version of <a href="https://knowledge.bsigroup.com/products/specification-for-identification-of-pipelines-and-services/standard">BS 1710</a>.</p><p>To identify what parts of a plumbing system they control, servicing valves should be labelled.</p><p>For further information please refer to the <a href="/publications/information-leaflets/">pipe identification information leaflet</a></p><p>&nbsp;</p><p>&nbsp;</p><p>&nbsp;</p><p>&nbsp;</p><p>&nbsp;</p><!--PARTBREAK--><h1 id="topics">FAQs</h1><!--PARTBREAK--><p><br></p>

How do you find out what the system maximum operating pressure is?

<h1 id="how-do-you-find-out-what">How do you find out what the system maximum operating pressure is?</h1><hr><h4 id="how-do-you-find-out-what"></h4><p>One way is to measure the supply pressure at a tap directly supplied from the mains at a time when there is little demand, such as at night.</p><p><strong>Please note:</strong></p><ul><li><p>This will not take into consideration any transient or surge pressures which may be generated within the system. For example water hammer resulting from the rapid closure of a valve within the system.</p></li><li><p>Water fittings must be able of accommodating 1½ times the maximum operating pressure.</p></li></ul><p>&nbsp;</p><p>&nbsp;</p><p>&nbsp;</p><!--PARTBREAK--><h1 id="topics">FAQs</h1><!--PARTBREAK--><p><br></p>

What are the temperatures requirements for cold water distribution?

<h1 id="what-are-the-temperatures-requirements-for">What are the temperatures requirements for cold water distribution?</h1><hr><h4 id="what-are-the-temperatures-requirements-for"></h4><p>To minimise the risk of contamination resulting from microbial growth and wastage due to taps left to run, cold water storage and distribution systems should be designed and installed to maintain a temperature not exceeding 20<sup>o</sup>C.</p><p>Plumbing systems should be designed and installed to ensure there is regular flow through.</p><p>To prevent undue warming, it is good practice to insulate both hot and cold water pipework. Unless it is adequately protected water fittings should not be installed where it could be exposed to heat sources, such as other services or sunlight.</p><p>For further information please refer to&nbsp;<a href="https://knowledge.bsigroup.com/products/specifications-for-installations-inside-buildings-conveying-water-for-human-consumption-general/standard">BS EN 806</a>,&nbsp;<a href="https://knowledge.bsigroup.com/products/guide-to-the-design-installation-testing-and-maintenance-of-services-supplying-water-for-domestic-use-within-buildings-and-their-curtilages-complementary-guidance-to-bs-en-807/tracked-changes">BS 8558</a> and&nbsp;<a href="https://www.hse.gov.uk/pubns/books/l8.htm">HSE Legionella ACOP.</a></p><p>&nbsp;</p><!--PARTBREAK--><h1 id="topicsfaqs">FAQs</h1><!--PARTBREAK--><p><br></p>

Can joints and water fittings which have specific operational functions be concealed?

<h1 id="can-joints-and-water-fittings-which">Can joints and water fittings which have specific operational functions be concealed?</h1><hr><h4 id="can-joints-and-water-fittings-which"></h4><p>Joints on concealed pipework are likely to lose their integrity over time and therefore should only be considered where unavoidable.</p><p>To prevent waste there needs to be provision to access any joints or water fittings which require maintenance, such as backflow prevention devices, valves which control the flow and any other operational fitting.</p><p>&nbsp;</p><p>&nbsp;</p><p>&nbsp;</p><!--PARTBREAK--><h1 id="topics">FAQs</h1><!--PARTBREAK--><p><br></p>

Why do customers need their own stop valves?

<h1 id="why-do-customers-need-their-own">Why do customers need their own stop valves?</h1><hr><h4 id="why-do-customers-need-their-own"></h4><p>Stop valves isolate the supply to premises.</p><p>To help minimise waste stop valves should be labelled to indicate what parts of a plumbing system they control.</p><p>Stop valves should be installed on the supply pipe in a readily accessible location either inside or immediately outside the premises.</p><p>In the case of properties with multiple occupants, such as a block of flats, in addition to the customers own stop tap, a stop valve for maintenance or communal use should be installed.</p><p>When selecting a stop valve for use by owner/occupiers consideration should be given to ease and speed of operation, including the effect of sudden changes in supply pressure.</p><figure class="img-responsive" style="width: 527px; float: none; margin-left: auto; margin-right: auto; min-width: auto; min-height: auto;"><img src="/images/topics/faqs/10.4-3nov23__002_.png" class="img-responsive" style="width: 100%"></figure><p>&nbsp;</p><p><strong>Please note:</strong> the illustrations above are examples of acceptable locations for stop valves. Whilst not shown other requirements apply, including but not limited to the installation of drain taps, servicing valves and backflow protection.</p><p>For further information contact the local <a href="https://www.waterregsuk.co.uk/contacts/water-company-contacts/">water undertaker.</a></p><p>&nbsp;</p><p>&nbsp;</p><!--PARTBREAK--><h1 id="topics">FAQs</h1><!--PARTBREAK--><p><br></p>

Does the local water undertaker need to know if there is an alternative water source at a premises?

<h1 id="does-the-local-water-undertaker-need">Does the local water undertaker need to know if there is an alternative water source at a premises?</h1><hr><h4 id="does-the-local-water-undertaker-need"></h4><p>Owners/occupiers should always ensure the local water undertaker is aware if a premises has both a mains drinking water and alternative water supply, such as a borehole or rainwater.</p><p>&nbsp;</p><p>&nbsp;</p><p>&nbsp;</p><!--PARTBREAK--><h1 id="topics">FAQs</h1><!--PARTBREAK--><p><br></p>

Can mains water supplies be connected to installations also supplied by another alternative source of water?

<h1 id="can-mains-water-supplies-be-connected">Can mains water supplies be connected to installations also supplied by another alternative source of water?</h1><hr><p>No. Alternative water supplies should never be directly connected to the mains drinking water.<br><br>Where mains water and other water sources, such as rainwater, recycled water, river water and borehole supplies, combine it is essential to notify the relevant water undertaker to ensure adequate backflow protection arrangements are installed.</p><p>The only legal and safe way to combine mains and another source of water is to use an arrangement called a break tank which enables separation of supplies. Typically, this is done using a Type AA or Type AB air gap the key features being:</p><ul><li><p>An unrestricted or weir spill over</p></li><li><p>The pipework supplying the mains water must be external to the tank</p></li><li><p>The mains water feed must discharge at a higher level than and maintain a minimum clearance (twice the internal diameter (2D) of the supply pipework or 20 mm whichever is the greater) from those another sources</p></li><li><p>The water in the tank should not come into contact with the mains water inlet for example as a result of splashing.</p><p><br></p></li></ul><p>&nbsp;</p><viewer-3d src="/downloads/3d/airbreaktank.gltf" x="-0.68" y="-0.1" z="-0.05"></viewer-3d><p>&nbsp;</p><!--PARTBREAK--><h1 id="topics">FAQs</h1><!--PARTBREAK--><p><br></p>

What is meant by a 'dead leg'?

<h1 id="what-is-meant-by-a-dead">What is meant by a 'dead leg'?</h1><hr><p>‘Dead leg’ or ‘blind end’ is a term used to describe a section of pipework (leg) containing water which is not turned over i.e. the water is stagnant (dead). For example, pipework which supplied a system that has been removed or is no longer in use (redundant).</p><p>&nbsp;</p><p>&nbsp;</p><p>&nbsp;</p><!--PARTBREAK--><h1 id="topics">FAQs</h1><!--PARTBREAK--><p><br></p>

Do 'dead legs' have to be removed?

<h1 id="do-dead-legs-have-to-be">Do 'dead legs' have to be removed?</h1><hr><h4 id="do-dead-legs-have-to-be"></h4><p>Yes, dead legs should be removed as they are a potential source of contamination. If the dead leg cannot be completely removed any blind end should be as short as possible.</p><p>All plumbing systems should be designed to ensure a steady through flow of water. For pipework supplying fittings which are used infrequently i.e. fire supplies or water reuse systems with a back-up supply, appropriate backflow protection should be installed as close as reasonably practicable to the mains or supply/distributing pipe.</p><p>&nbsp;</p><p>&nbsp;</p><!--PARTBREAK--><h1 id="topics">FAQs</h1><!--PARTBREAK--><p><br></p>

Is the pressure testing specified in BS EN 806 acceptable?

<h1 id="is-the-pressure-testing-specified-in">Is the pressure testing specified in BS EN 806 acceptable?</h1><hr><h4 id="is-the-pressure-testing-specified-in"></h4><p>Yes.</p><p>The pressure testing requirements specified in BS EN 806 recommends that plumbing installations and fittings be tested at 1.1 times the maximum working pressure rather than the 1.5 times required by the Water Supply (Water Fittings) Regulations, Byelaws in Scotland.</p><p>However due to the terms and definitions applied rather than advocating a lower pressure test than that required by the UK national requirements BS EN 806 actually recommends a slightly higher test pressure. With the result that should an installation be designed to satisfy the pressure test recommendations given in BS EN 806, then it will by default comply with those of the Water Fittings Regulations /Byelaws<br><br><strong>Summary of requirements of BS EN 806:</strong></p><p style="margin-left:20px;">BS EN 806: Part 1 defines maximum design pressure (MDP) of a system as:-</p><p style="margin-left:40px;">‘the maximum hydrostatic pressure at which the potable water installation is designed to work’</p><p style="margin-left:20px;">BS EN 806: Part 2 covers design, clause 3.4.2 which covers strength states:-</p><p style="margin-left:40px;">‘To ensure adequate strength, all components of the system shall be designed to meet the test pressure requirements of the local and national laws and regulations. The test pressure shall be at least 1.5 times the allowable maximum operating pressure (PMA).’</p><p>Therefore the maximum design pressure should be at least 1.5 times the maximum operating pressure.</p><p style="margin-left:40px;">MDP = 1.5 x maximum operating pressure</p><p>To comply with the requirements of schedule 2 paragraph 15 (1) a backflow prevention device or arrangement rated to at least fluid category 2 must be installed Fittings Regulations/Byelaws require the system to be pressure tested at:-</p><p style="margin-left:40px;">1½ x 5 bar =7.5 bar</p><p style="margin-left:20px;">BS EN 806 recommends a test pressure of:-</p><p style="margin-left:40px;">1.1 x maximum design pressure (MDP)</p><p style="margin-left:40px;">where</p><p style="margin-left:40px;">MDP = 1½ x maximum operating pressure<br>1.1 x [1½ x 5 bar] = 8.25 bar</p><p>&nbsp;</p><hr><!--PARTBREAK--><h1 id="topics">FAQs</h1><!--PARTBREAK--><p><br></p>

How close can water pipes be laid to other services?

<h1 id="how-close-can-water-pipes-be">How close can water pipes be laid to other services?</h1><hr><h4 id="how-close-can-water-pipes-be"></h4><p>The recommended distances between utilities can be found in the latest National Joint Utilities Group (NJUG) guidelines. Where these dimensions and depths cannot be achieved protective measures will be required.</p><p>All pipework whether installed above or below ground should be marked in accordance with the requirements of the latest version of <a href="https://knowledge.bsigroup.com/products/specification-for-identification-of-pipelines-and-services/standard">BS 1710.</a></p><p>If the installation of the pipework is notifiable, under regulation 5 of the water fittings regulations in <a href="https://www.legislation.gov.uk/uksi/1999/1148/contents/made">England, Wales</a> and <a href="https://www.legislation.gov.uk/nisr/2009/255/contents/made">Northern Ireland</a>, <a href="https://www.scottishwater.co.uk/-/media/ScottishWater/Document-Hub/Business-and-Developers/Byelaws-and-Trade-Effluent/170718swbyelawsexplained.pdf">byelaws in Scotland</a>, installation advice should be provided as part of the notification process.</p><p>If it is not notifiable there remains a legal obligation for the premises owner or occupier to ensure the plumbing work is fully compliant with the water fittings regulations, byelaws in Scotland.</p><p>&nbsp;</p><p>&nbsp;</p><!--PARTBREAK--><h1 id="topics">FAQs</h1><!--PARTBREAK--><p><br></p>

Do drinking water supplies need to be separated from fluids in primary systems and closed circuits?

<h1 id="new-pagedo-drinking-water-supplies-need">Do drinking water supplies need to be separated from fluids in primary systems and closed circuits?</h1><hr><p>Yes, appropriate separation is required. Minimising the risk of contaminated fluids coming into contact with water to be used for domestic purposes (drinking, bathing, washing, cooking etc) is a key objective of the water fittings regulations/byelaws.</p><p>Mindful of the need to ensure sufficient safeguards are in place to address the possibility of drinking water supplies coming into contact with fluids which are not considered to be wholesome, in determining whether systems making use of heat recovery or exchange are compliant with regulation 4(1) the following factors will be taken into consideration. Please note decisions will be taken on a case by case basis.</p><ul><li><p>The actual fluid categories of the fluids within the system.</p></li><li><p>How readily identifiable any potential integrity failure of the system would be.</p></li><li><p>Whether the system design meets the requirements for single or double wall separation specified in BS EN 1717.</p></li></ul><p><br></p><!--PARTBREAK--><h1 id="topics">FAQs</h1><!--PARTBREAK--><p><br></p>

What is adequate support?

<h1 id="new-pagewhat-is-adequate-support">What is adequate support?</h1><hr><p>The method of support and spacing between supports will be dependent on the type of water fitting and material it is constructed from.</p><p>In the case of pipework allowance should be made to accommodate likely movement for example thermal expansion and contraction.</p><p>Useful sources of information include <a href="https://knowledge.bsigroup.com/products/specifications-for-installations-inside-buildings-conveying-water-for-human-consumption-general/standard" target="_blank">BS EN 806:4</a>, and <a href="https://knowledge.bsigroup.com/products/guide-to-the-design-installation-testing-and-maintenance-of-services-supplying-water-for-domestic-use-within-buildings-and-their-curtilages-complementary-guidance-to-bs-en-807/tracked-changes" target="_blank">BS 8558</a>.</p><p><br></p><!--PARTBREAK--><h1 id="topics">FAQs</h1><!--PARTBREAK--><p><br></p>

What is meant by concealed?

<h1 id="new-pagewhat-is-meant-by-concealed">What is meant by concealed?</h1><hr><p>Water fittings considered to be concealed include those:</p><ul><li><p>Buried in the ground</p></li><li><p>Installed below or embedded in floors</p></li><li><p>Installed in or behind wall finishes</p><p><br></p></li></ul><p>Water fittings considered not to be concealed include those:</p><ul><li><p>Installed below ground but not buried, such as in a chamber or basement room</p></li><li><p>Installed below floors or in walls which can be readily accessed</p></li></ul><p><br></p><p><img src="/images/topics/faqs/meant_by_concealed.png" class="img-responsive" style=""></p><!--PARTBREAK--><h1 id="topics">FAQs</h1><!--PARTBREAK--><p><br></p>

Can joints and water fittings be concealed?

<h1 id="new-pagecan-joints-and-water-fittings">Can joints and water fittings be concealed?</h1><hr><p>Joints on concealed pipework are likely to lose their integrity over time and therefore should only be considered where unavoidable.</p><p>To prevent waste there needs to be provision to access any joints or water fittings which require maintenance, such as backflow prevention devices, valves which control the flow and any other operational fitting.</p><p><br></p><!--PARTBREAK--><h1 id="topics">FAQs</h1><!--PARTBREAK--><p><br></p>

How should concealed water fittings be installed in walls?

<h1 id="new-pagehow-should-concealed-water-fittings">How should concealed water fittings be installed in walls?</h1><hr><p>All domestic hot and cold water system pipework concealed within walls should:</p><ul><li><p>Be installed with a minimum number of joints. This is because joints are prone to a loss of integrity over time and therefore should only be considered where unavoidable.</p></li><li><p>Be installed in a chase/duct or void. Wrapping pipework in insulation is not an acceptable method of ducting or passing through a chimney is not an acceptable method of ducting.</p></li><li><p>With the agreement of the local water undertaker pipework may be installed alongside other services in a shared duct. An example of what may be considered as acceptable is shown below.</p></li><li><p>Be appropriately clipped to avoid water hammer and other stresses which would affect the integrity of the installation.</p></li><li><p>Be insulated with a suitable gap maintained between the cold water, hot water and any other heat source to prevent heat transfer or loss.</p></li><li><p>Not be embedded or come into contact with other materials such as plaster or cement.</p></li><li><p>Be accessible to enable inspection and replacement. Further information about accessibility can be found in BS 8558.</p></li></ul><p>Below are images illustrating domestic hot and cold water systems concealed in a wall and a soil pipe duct.</p><p><br></p><p><img src="/images/topics/faqs/concealed_water_fittings_in_walls.png" class="img-responsive" style="width: 90%; float: none; margin-left: auto; margin-right: auto;"></p><p><br></p><!--PARTBREAK--><h1 id="topics">FAQs</h1><!--PARTBREAK--><p><br></p>

How should concealed water fittings be installed in floors?

<h1 id="new-pagehow-should-concealed-water-fittings">How should concealed water fittings be installed in floors?</h1><hr><p>All domestic hot and cold water system pipework concealed within floors should:</p><ul><li><p>Be installed with a minimum number of joints. This is because joints are prone to a loss of integrity over time and therefore should only be considered where unavoidable.</p></li><li><p>Be installed in a chase/duct or void. Wrapping pipework in insulation is not an acceptable method of ducting.</p></li><li><p>Be appropriately clipped to avoid water hammer and other stresses which would affect the integrity of the installation.</p></li><li><p>Be insulated with a suitable gap maintained between the cold water, hot water and any other heat source to prevent heat transfer or loss.</p></li><li><p>Not embedded or come into contact with other materials such as backfill, screed or cement.</p></li><li><p>Be accessible to enable inspection and replacement. Further information about accessibility can be found in <a href="https://knowledge.bsigroup.com/products/guide-to-the-design-installation-testing-and-maintenance-of-services-supplying-water-for-domestic-use-within-buildings-and-their-curtilages-complementary-guidance-to-bs-en-807/tracked-changes" target="_blank">BS 8558</a>.</p></li></ul><p><br></p><p><img src="/images/topics/faqs/concealed_water_fittings_in_floors.png" class="img-responsive" style="width: 90%; float: none; margin-left: auto; margin-right: auto;"></p><!--PARTBREAK--><h1 id="topics">FAQs</h1><!--PARTBREAK--><p><br></p>

How should underfloor heating be installed?

<h1 id="newhow-should-underfloor-heating-be-installed">How should underfloor heating be installed?</h1><hr><p>Underfloor heating systems should be installed in a manner considered to be acceptable to building control and the local water undertaker.</p><p>If domestic supplies are to be installed in close proximity to underfloor heating, they should:</p><ul><li><p>Be installed as a single run of pipework without any inaccessible joints below the underfloor heating insulation.</p></li><li><p>To prevent heat transfer or loss any supply pipework should be laid with a suitable gap maintained between the hot and cold systems and both wrapped in insulation.</p></li></ul><p><img src="/images/topics/faqs/underfloor_heating.png" class="img-responsive" style="width: 90%; float: none; margin-left: auto; margin-right: auto;"></p><!--PARTBREAK--><h1 id="topics">FAQs</h1><!--PARTBREAK--><p><br></p>

How should outdoor below ground services be installed?

<h1 id="newhow-should-outdoor-below-ground-services">How should outdoor below ground services be installed?</h1><hr><p>Firstly, the pipe and fittings, including method of connection, should be suitable for below ground use and the environment in which they are to be installed. Joints should be kept to a minimum. Water fittings which are susceptible to permeation by hydrocarbons should not be laid in ground near installation storing or ground contaminated with petrol or oil unless protected.</p><p>Pipework should be laid at a depth of not less than 750 mm (to limit the effect of freezing and mechanical damage) and no greater than 1350 mm deep. They should be embedded in nonabrasive materials. Where this cannot be achieved in all circumstances the consent of the local water undertakers must be obtained via notification.</p><p>Where the local water undertaker consents to pipework being laid at less than 750 mm it should be installed as deep as possible below ground level and protected against warming, freezing and mechanical damage (for example due to ground movement).</p><p>Pipework should not be installed above ground level is not permitted without the agreement of the local water undertaker.</p><p><img src="/images/topics/faqs/outdoor_below_ground_services.png" class="img-responsive" style="width: 90%; float: none; margin-left: auto; margin-right: auto;"></p><!--PARTBREAK--><h1 id="topics">FAQs</h1><!--PARTBREAK--><p><br></p>

Are there any methods for avoiding below ground obstructions?

<h1 id="neware-there-any-methods-for-avoiding">Are there any methods for avoiding below ground obstructions?</h1><hr><p>Examples of how to avoid below ground obstructions are given below. Please note the local water undertaker should be consulted before laying pipework over an obstruction.</p><p><br></p><p><img src="/images/topics/faqs/avoiding_below_ground_obstructions-1.png" class="img-responsive" style="width: 90%; float: none; margin-left: auto; margin-right: auto;"><img src="/images/topics/faqs/avoiding_below_ground_obstructions-2.png" class="img-responsive" style="width: 90%; float: none; margin-left: auto; margin-right: auto;"></p><p><br></p><!--PARTBREAK--><h1 id="topics">FAQs</h1><!--PARTBREAK--><p><br></p>

Can pipework be laid in a contaminated environment?

<h1 id="new-pagecan-pipework-be-laid-in">Can pipework be laid in a contaminated environment?</h1><hr><p>Pipework should never be installed in a contaminated environment such as a sewer or cesspool.</p><p>Non-metallic (plastic) plumbing fittings are at risk of permeation by diesel or heating fuel, pesticides, insecticides and similar organic substances or fluids, so should never be installed where they could come into direct contact, including contact with soil contaminated with them.</p><p>Where this is unavoidable contact the local water undertaker for advice.</p><!--PARTBREAK--><h1 id="topics">FAQs</h1><!--PARTBREAK--><p><br></p>

Can non-metallic fittings be laid close to gas services?

<h1 id="newcan-non-metallic-fittings-be-laid">Can non-metallic fittings be laid close to gas services?</h1><hr><p>Non-metallic water fittings which are susceptible to permeation should not be installed in close proximity to other services for example gas pipelines, or in ground contaminated with hydrocarbons or other contaminants of concern.</p><p>For further advice contact the local water undertaker.</p><!--PARTBREAK--><h1 id="topics">FAQs</h1><!--PARTBREAK--><p><br></p>

What is the recommended distance between water services and other utilities?

<h1 id="newwhat-is-the-recommended-distance-between">What is the recommended distance between water services and other utilities?</h1><hr><p>The recommended distances between utilities can be found in the latest National Joint Utilities Group (NJUG) guidelines. Where these dimensions and depths cannot be achieved protective measures will be required.</p><p>If the installation of the pipework is notifiable, under regulation 5 of the water fittings regulations in <a href="https://www.legislation.gov.uk/uksi/1999/1148/contents/made" target="_blank">England, Wales</a> and <a href="https://www.legislation.gov.uk/nisr/2009/255/contents/made" target="_blank">Northern Ireland</a>, <a href="https://www.scottishwater.co.uk/-/media/ScottishWater/Document-Hub/Business-and-Developers/Byelaws-and-Trade-Effluent/170718swbyelawsexplained.pdf" target="_blank">byelaws in Scotland</a>, installation advice should be provided as part of the notification process.</p><p>If it is not notifiable there remains a legal obligation for the premises owner or occupier to ensure the plumbing work is fully compliant with the water fittings regulations, byelaws in Scotland.</p><p><br></p><!--PARTBREAK--><h1 id="topics">FAQs</h1><!--PARTBREAK--><p><br></p>

How should pipework access a building?

<h1 id="newhow-should-pipework-access-a-building">How should pipework access a building?</h1><hr><p>The supply pipe to a building should enter at a depth of 750 mm.</p><p>Pipework passing through walls and laid at depths of less than 750 mm, including any inside the building should be ducted. This is to prevent damage and facilitate ease of replacement, the internal surface of the ducting should be smooth bore i.e. any ridging to be external only.</p><p>The pipework should be sealed using a method acceptable to the local water undertaker. This is to prevent ingress of gases and vermin. It should also be adequately insulated. Where pipework is installed below a suspended floor if there is an air vent the pipework should be ducted and insulated to the finished floor level.</p><p>In premises where there will be no water demand or a positive change to the ambient temperature after 12 hours, the <a href="/publications/calculators/">insulator calculator</a> can be used to give an indication of insulation requirements. Where this is not likely to be the case the local water undertaker should be consulted as insulation alone may not be suitable. Example of pipework entering a building at and below street level are given below.</p><p><img src="/images/topics/faqs/pipework_access.png" class="img-responsive" style="width: 90%; float: none; margin-left: auto; margin-right: auto;"></p><p><img src="/images/topics/faqs/pipework_access-2.png" class="img-responsive" style="width: 90%; float: none; margin-left: auto; margin-right: auto;"></p><p><br></p><!--PARTBREAK--><h1 id="topics">FAQs</h1><!--PARTBREAK--><p><br></p>

Are there any specific requirements for plumbing installed above ground?

<h1 id="new-pageare-there-any-specific-requirements">Are there any specific requirements for plumbing installed above ground?</h1><hr><p>In addition to the requirements already listed, above ground plumbing must be protected against environmental conditions, accidental, mechanical and animal damage.</p><p>A regular inspection should be undertaken of pipework and water fittings to identify leaks or other issues. This will help to reduce waste, prevent contamination and save cost.</p><p><br></p><!--PARTBREAK--><h1 id="topics">FAQs</h1><!--PARTBREAK--><p><br></p>

What protection against freezing is required?

<h1 id="newwhat-protection-against-freezing-is-required">What protection against freezing is required?</h1><hr><p>The type and level of frost protection required will depend upon the environment in which a water fitting is installed, with insulation and trace heating commonly used.</p><p>Any water fitting installed outside the thermal envelope or at depths of less than 750 mm should be protected against damage caused by freezing.</p><p>Any not used during cold weather, such as seasonal irrigation systems should be isolated and drained down. Similarly, if a premises is to be left unoccupied and unheated during cold weather, for example a holiday home or caravan, the water supply should be turned off and plumbing system drained.</p><p>When installed in accordance with the manufacturer’s instructions insulation may delay but not prevent freezing.</p><p>Providing within 12 hours the plumbing system is used (there is demand flow) or there is an increase in the ambient temperature, the <a href="/publications/calculators/" target="_blank">insulator calculator</a> can be used to give an indication of insulation requirements for installations exposed to low temperatures. Where this is not likely to be the case the local water undertaker should be consulted as insulation alone may not be suitable.</p><p><br></p><!--PARTBREAK--><h1 id="topics">FAQs</h1><!--PARTBREAK--><p><br></p>

Regulations & Byelaws which apply include but are not limited to:


  • Regulation 5 England & Wales

  • Regulation 5 Northern Ireland 

  • Byelaw 5 Scotland 

  • Schedule 2 paragraph 2

  • Schedule 2 paragraph 3

  • Schedule 2 paragraph 4

  • Schedule 2 paragraph 5

  • Schedule 2 paragraph 6 

  • Schedule 2 paragraph 7

  • Schedule 2 paragraph 8

  • Schedule 2 paragraph 9

  • Schedule 2 paragraph 10

  • Schedule 2 paragraph 11

  • Schedule 2 paragraph 12

  • Schedule 2 paragraph 13

  • Schedule 2 paragraph 14

  • Schedule 2 paragraph 15

  • Schedule 2 paragraph 20

  • Schedule 2 paragraph 24

  • Schedule 2 paragraph 27

  • Schedule 2 paragraph 30

  • Schedule 2 paragraph 31



  • Regulation 5 England & Wales

  • Regulation 5 Northern Ireland

  • Byelaw 5 Scotland

  • Schedule 2 paragraph 2

  • Schedule 2 paragraph 3

  • Schedule 2 paragraph 4

  • Schedule 2 paragraph 7

  • Schedule 2 paragraph 8

  • Schedule 2 paragraph 9

  • Schedule 2 paragraph 11

  • Schedule 2 paragraph 12

  • Schedule 2 paragraph 13

  • Schedule 2 paragraph 14

  • Schedule 2 paragraph 15

  • Schedule 2 paragraph 20

  • Schedule 2 paragraph 27


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