Self Lay Policy and
Company Specific Addendum
21 December 2015
Contents
Introduction
Contacting STW
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Part 1: Self Lay Policy
Introduction
Accreditation
Non Contestable
Contestable Work
Initial Enquiry
Making an Application for a New Water Main
Design
Offer Letter
Developer Response
Self Lay Agreement
Pre-start Meeting
The Role of the STW Customer Experience Manager
Risk and Contingency Plan
Construction
Sub Contracting
Commissioning
Audit and Compliance
Adoption of the mains
Asset Value Payments
Service Connections
Metering
Site sign-off
Self Lay Policy and Process Compliance
Levels of Service
Disputes
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Part 2: Severn Trent Water’s Addendum
Part 1 – General
Part 2 – Self Lay Procedures
Part 3 – Design and Construction Guidance
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Self Lay Policy & Addendum
Introduction
This document defines Severn Trent Water’s (STW) self lay policy and company specific addendum
to the WRc publication Self-Laying of Water Mains and Services – A Code of Practice for
England and Wales (2nd Edition) (Code of Practice). The policy and addendum should be read
and followed by self lay organisations (SLOs) constructing new mains schemes and undertaking
water connections in the STW operating area.
If this is a printed copy, you are advised to check that this is a current version. Please visit our website at
stwater.co.uk/developers/self-lay/self-lay
Part 1 of this document explains how STW manages self lay activities and how it interacts with SLOs.
Part 2 of this document specifies where STW have variations from the Code of Practice.
This document should also be read in conjunction with the following publications and internal documents
available to all accredited SLOs:

The WRc publication Self-Laying of Water Mains and Services – A Code of Practice for England and
Wales (2nd Edition) – this can be found here selflay.wrcplc.co.uk/

All relevant legislation including but not limited to the Water Industry Act 1991, the Highways Act
1980, the New Roads and Street Works Act 1991 all as may be amended from time to time

STW’s Design Manual

Civil Engineering Specification for Water Industry (7th edition) – this can be found at
sfa.wrcplc.co.uk/ceswi-7th-edition.aspx
STW values working alongside our SLOs and adheres to Ofwat’s expectation of fair competition and therefore:
1. We will not insist on laying all new water mains
2. We will charge reasonable costs for any work that we do
3. Our costs will be transparent
4. Our communications with SLOs will be accurate and clear and easy to find
5. We will not impose unreasonable conditions or working practices on SLOs
Contacting STW
The initial point of contact for any enquiry about self-lay should be sent to:
Developer Services
Severn Trent Water Limited
PO Box 5311
Coventry
CV3 9FL
Telephone: 0800 707 6600
Email: new.connections@severntrent.co.uk
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Self Lay Policy & Addendum
Part 1: Self Lay Policy
Introduction
In accordance with section 51A of the Water Industry Act 1991, Severn Trent Water (STW) will agree
to adopt a new water main that has been laid by a third party, subject to the following
requirements:
1.
2.
3.
The work has been done in accordance with section 51A of the Water Industry Act 1991
The work has been done in accordance with the current UK Water Industry Research (UKWIR) SelfLaying of Water Mains and Services - A Code of Practice for England and Wales 2nd Edition (the
Code of Practice) as amended by Severn Trent Water’s Self Lay Policy and Company Specific
Addendum (the Addendum) to the Code of Practice. The Code of Practice can be found at
http://selflay.wrcplc.co.uk.
In addition to compliance with the Code of Practice and the STW Addendum, all work undertaken by
Self Lay Organisations (SLOs) must be compliant with STW’s Design Manual.
Accreditation
Developers can appoint a SLO to construct a new water main and /or lay a new service supply pipe, but all
work must be carried out by an accredited SLO. To ensure the quality and safety of the work undertaken by
SLOs, STW recognise the accreditation scheme operated by Lloyd’s Register and a list of accredited SLOs can
be found at http://www.lr.org/en/energy/utilities-and-building-assurance-schemes/water-industryregistration-scheme/
Designers and installers need to meet the accreditation criteria set out in Water Industry Registration Scheme
(WIRS) Requirements Document – see here http://www.lr.org/en/energy/utilities-and-building-assuranceschemes/water-industry-registration-scheme/wirs-accreditation-for-self-lay-organisations.aspx before we
agree to the construction of mains and service supply pipes.
Non Contestable Work
Due to the need to safeguard the water supply to our existing customers, there are restrictions to the work
that an SLO can do. Some work must remain STW’s responsibility so that we meet our obligation to maintain a
wholesome and safe water supply to our customers. STW therefore reserves the right to carry out all work
defined as non contestable. However, in some circumstances STW may be willing to allow some of these
activities to be carried out by the SLO by prior agreement.
This non-contestable work includes:
• Designing ‘off-site’ water systems, which involves improving our existing network to cope with the additional
demand
• Sizing water pipes
• Approving on-site water main designs
• Off-site work to provide additional capacity to the existing water distribution network
• Determining the timing of service pipe connections to a new main
• Determining the timing of routine in line mains connections
• Connecting a new main to our existing water distribution network
• Connecting a new main to an existing main, when this involves risks to existing customers
• Connecting a service pipe directly to an existing main, when there is a risk to existing customers
• Water sampling and quality testing
• Decommissioning redundant mains following a diversion
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Self Lay Policy & Addendum
In accordance with the Water Industry Act 1991 (the “Act”), some of STW’s costs in carrying out non
contestable work will be payable by the Developer or SLO.
Contestable Work
This is the work that can be carried out by SLOs and includes:
• Designing on-site water systems in line with STW specifications
• Installing on-site mains
• Making routine in-line mains connections, subject to relevant safeguards and accreditation schemes being in
place
• Installing off-site mains in third party land and highways where SLOs have obtained the necessary easements
and highway authority approvals, and satisfied any other legal requirements
• Installing new mains for development sites, where SLOs have the necessary permissions and no existing
customers will be affected and/or there are no engineering reasons why this work should be non-contestable
• Installing service pipes to our specifications
• Connecting service pipes to new mains (after STW have commissioned them), provided the appropriate
standards are met and there are no risks to existing customers
• Connecting service pipes for new development sites to water mains installed by STW or other SLOs
• Connecting service pipes directly to existing off-site mains, subject to appropriate accreditation, approvals
and controls
• Swabbing, pressure testing and disinfecting new mains under supervision
• Fitting water meters to our specifications and subject to our approval
• Providing ‘as constructed’ drawings to our specifications
Initial Enquiry
If the development site has not yet reached the planning approval stage, or a SLO just wants to know if the
proposed development site can be supplied with water, a SLO can send STW a development enquiry before
making a full application. It will also confirm if the development will affect existing STW assets.
Any party involved in a self lay development can make an application for a development enquiry by completing
a developer enquiry application form and sending it to us along with the following supporting documents:
 A location plan
 A copy of a site layout plan
 Full details of the proposed development including flows/storage details
 The current application fee which can be found in our Developer Charges booklet on our website https://www.stwater.co.uk/developers/application-forms-and-guidance-notes/
The application form for a development enquiry can be found on our website here:
https://www.stwater.co.uk/developers/application-forms-and-guidance-notes/
Once complete, the application form and application fee payment can be posted to us at:
Developer Services
Severn Trent Centre
PO Box 5311
Coventry
CV3 9FL
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Self Lay Policy & Addendum
Or you can email the application form to us at new.connections@severntrent.co.uk attaching all supporting
documentation. If the application form is sent to us by email, we’ll assume that the applicant wants to pay the
application fee payment by credit or debit card and we’ll call to take the payment.
The current application fee can be found in our Developer Charges booklet on our website https://www.stwater.co.uk/developers/application-forms-and-guidance-notes/
Once we’ve received the application form we’ll confirm receipt and provide a reference number. The
application will then be assigned to a member of our team who will be the point of contact during this stage.
The application fee covers the work we need to do to respond to an enquiry. If the flow requirements are such
that more extensive modelling/evaluation is needed an additional payment may be required for the
completion of a Network Impact Assessment. We’ll tell you if we need an additional payment in our enquiry
response.
The more information that can be given about the development type and the water usage, the more detailed
and tailored our response can be. Our standard response for water enquires will include:
 A copy of our water records for the area
 Confirmation of any apparatus we have that will be affected by the proposals
 Information about our ability to provide water for the development and how it should be supplied
 Where appropriate details of any offsite works needed to reinforce our network to supply the
development
 Estimated costs associated for the water mains or service connections proposed to serve the site
Making an Application for a New Water Main
Any party involved in a self lay development can make an application for a new water main.
The application form for a new water main can be found on our website here:
https://www.stwater.co.uk/developers/application-forms-and-guidance-notes/
Once complete, the application form and application fee payment can be posted to us at:
Developer Services
Severn Trent Centre
PO Box 5311
Coventry
CV3 9FL
Or email the application form to us at new.connections@severntrent.co.uk attaching all supporting
documentation. If you send the application to us by email, we’ll assume that you want to pay the application
fee payment by credit or debit card and we’ll call to take the payment.
The current application fee can be found in our Developer Charges booklet on our website here:
stwater.co.uk/developers/application-forms-and-guidance-notes/
The application needs to tell us about all relevant parties to the Self Lay Agreement, such as the Developer, the
SLO and any third party land owners.
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Self Lay Policy & Addendum
Once we’ve received the application we’ll confirm receipt and give you a reference number. The application
will then be assigned to a member of our design team who will be your point of contact during the design
stage.
A WIRS accredited designer can prepare and send STW a design for a new water mains scheme along with the
application form, which we will either approve or highlight aspects of the design that don’t meet our
specifications, as set out in our Design Manual and Addendum. The designer must consult with the local Fire
and Rescue Service (FRS) when designing a scheme.
Design
If a STW requisitioned design has previously been prepared, this may be used by a WIRS accredited designer.
We reserve the right to charge for the conversion of an approved design. The current charge can be found in
our Developer Charges booklet on our website here: stwater.co.uk/developers/application-forms-andguidance-notes/
If an accredited designer needs to vary a design once construction has started he should contact the design
team in writing at NewConnections.SelfLayTeam@severntrent.co.uk who will assess the impact of the
changes needed. We reserve the right to recover reasonable costs in relation to any changes.
Once a design has been reworked by a designer it can be sent back to STW for approval and once approved
we’ll either be able to provide costings for the scheme in our Offer Letter, or confirm that the design is
acceptable.
Offer Letter
The Offer Letter is designed to allow the developer to make a choice about who he wants to lay the new water
main and/or service connections. It can be laid by either STW, which is known as a requisition or a SLO, which
is known as self lay.
STW will show the costings for both requisition and self lay and they are valid for 6 months. This means that a
Developer has 6 months in which to make a decision about the option he wants to use. If the Developer comes
back to STW after 6 months he will incur another charge to provide new cost options.
The letter will show the work needed for the new water mains scheme, including what the site specific
contestable activity is, and the assumptions that the costings have been based on.
Developer Response
Within the Offer Letter there is an Acceptance of Proposal document which the developer can use to tell STW
whether the work is to be completed by STW as a requisition, or whether he has appointed a SLO. If self lay,
the developer will also need to tell STW who the point of contact will be for the site, i.e. the developer or their
appointed SLO, and who the Asset Value Payment will be paid to. STW don’t expect any payment at this time.
Self Lay Agreement
A Self Lay Agreement (Agreement) must be signed by all relevant parties before work can start on a
development site and it’s the developer’s responsibility to ensure they have the correct signed Agreement in
place before any work on site begins.
Relevant parties include:
 Self Lay Organisation
 Developer
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Self Lay Policy & Addendum


Severn Trent Water
Landowners
Pre start Meeting
A pre start meeting must take place before any work can start on a development site and STW expect the
following parties to attend:




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The developer
The SLO
STW’s third party contractor
STW’s Customer Experience Manager
Any other interested party
The purpose of the pre-start meeting is to agree such things as the build programme, to review drawings, to
agree the location of off site/spur main and possible delivery date, to review traffic management, to discuss
good and bad practice on site and find solutions to key issues. Where possible, the Notification to start
constructing a new water main (Form 2) should be completed.
The minutes of the meeting will be documented by the STW Customer Experience Manager and sent to all
attendees and will be held by STW against the records for the mains scheme.
The Role of the STW Customer Experience Manager
The Customer Experience Manager (CEM) is the STW representative on site. Their role is to oversee the
construction on site from inception to completion.
The CEM is expected to attend the pre-start meeting, visit the development site at least once a month and is
the point of contact for any issues on site.
Risk and Contingency Plan
In order to protect the integrity of the STW network and maintain a quality water supply to our existing
customers, STW will complete a risk assessment on the connection being made and may insist that a Risk and
Contingency Plan (R&C Plan) is in place before any connection is made to our existing network.
The risk assessment will be completed by STW and a R&C Plan will be documented by STW after the design has
been approved and the pre-start meeting has taken place.
Construction
Before any work can start on a development site, STW insist on the following:
 A pre-start meeting with all parties must have taken place and be minuted
 STW have approved the design of the mains scheme
 A signed Self Lay Agreement is in place
 A Risk & Contingency Plan is in place, where necessary
 STW have received a complete materials and fittings list
Failure to have these in place before work starts on site will be deemed a failure of process and the SLO will be
reported to Lloyd’s Register.
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Self Lay Policy & Addendum
If any installation of the new water main scheme is carried out without prior authority from STW, the SLO will
need to demonstrate that the work has been carried out to the requirements and specifications of STW. If any
work is done without approval, STW may refuse to vest and connect the main.
A SLO must tell STW when they are about to start construction on site by sending us a completed Notification
to start constructing a new water main (Form 2) 15 days before any work starts.
STW expect the minimum information on a Form 2:
1. The STW reference number(s)
2. The date the SLO intends to start work on site
3. A description of the works
4. The name/organisation who is going to carry out the testing and chlorination and their telephone number
5. The date of the pre-start meeting
6. The expected date of the final connection
7. Who is going to do the final connection
STW expects the SLO to send a copy of the Form 2 to Lloyd’s Register and to the STW Customer Experience
Manager.
An incomplete Form 2 will be returned to the SLO and this may delay the start of main laying.
Sub Contracting
Where a SLO intends to subcontract any part of the self-lay works they must notify STW. The SLO named on
the Agreement remains responsible for ensuring any work is completed in accordance with the Agreement and
this document. Any subcontractor must be WIRS accredited.
Commissioning
A SLO must tell STW when they want to connect the new water main by sending us a completed Water mains
sampling and commissioning notification (Form 3) 10 days before the connection is needed.
STW expect this minimum information on a Form 3:
1. The STW reference number(s)
2. Confirmation who is going to make the final connection. If this is the SLO, then we also need a Routine
Inline Mains Connection Notification
3. Confirmation that this is the final Form 3, if applicable
STW also expect the following documentation to be submitted with the Form3:
1. The Pressure Test and Chlorination Certificate
2. The Fire Hydrant Adoption Certificate issued to the local Fire & Rescue Service (FRS)
3. Copy of the Swabbing Record
4. 3 copies of the As-Laid Drawing(s) clearly marked with sampling and connection points along with SLO and
Developer’s name, STW reference number, scheme number, scheme name, scheme type, stage number, date
of completion of the scheme or phase and the date of submission. Where SLO and Severn Trent Water
software is compatible, drawings should be submitted electronically
5. The Asset Data update form
6. The site sign off sheet
STW expects the SLO to send a copy of the Form 3 to Lloyd’s Register and the STW Customer Experience
Manager.
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Self Lay Policy & Addendum
An incomplete Form 3 will be returned to the SLO and this may delay the connection.
Under no circumstances should a connection be made without confirmation of a passed water quality sample
from STW. Any connection done without this approval will be reported to Lloyd’s Register. Works will have to
stop while STW assess the impact on the water quality in the area and will seek to recover any additional costs
from the SLO involved in this work.
STW will permit the connection of the self laid main when it has been laid in compliance with the provisions of
the Agreement. Until that point the self laid main remains the responsibility of the Developer or SLO.
Audit and Compliance
Throughout construction, STW will conduct routine site visits and complete an audit of works to ensure that
the mains are being laid to specifications and the correct fixtures are used. It is expected that any works that
are found to be defective will be corrected by the SLO at no cost to STW.
During construction, STW expect the Gang Whereabouts in the STW area to be sent to both the STW CEM and
STW’s design team at NewConnections.SelfLayTeam@severntrent.co.uk each week.
Adoption of the mains
Once the main is laid and successfully commissioned, it becomes STW’s responsibility and we will issue a
Vesting Certificate confirming adoption of the main.
Although the main is adopted by STW there is a defects liability period of 12 months, during which time the
SLO is responsible for the repair of any defects. This 12 month period starts from the issuing of a Vesting
Certificate.
Asset Value Payments
When STW adopts the self laid main, or any part thereof, we will pay the Developer or the SLO an Asset Value
Payment (AVP) as detailed in the Offer Letter. STW will retain 10% of the final AVP until the final site sign off
has been completed and there is no corrective work needed on the adopted self-laid mains.
Service Connections
Service connections can also be laid by a SLO, as long as the installer carries the appropriate Water Industry
Registration Scheme (WIRS) accreditation.
Service connections can be taken from the on-site mains when the service supply pipes comply with The
Water Supply (Water Fittings) Regulations 1999 (the Regulations) and have either passed an STW inspection
process or have been laid by a STW Watermark, or equivalent scheme, accredited plumber. Details of the
Regulations can be found here: legislation.gov.uk/uksi/1999/1148/contents/made.
Details of STW’s Watermark scheme can be found on our website here: stwater.co.uk/businesses/watermarkplumbers/what-is-the-watermark-scheme/ . Although a plumber may be accredited under our Watermark, or
equivalent, scheme we reserve the right to audit 10% of service supply pipes.
Service connections to existing mains which are adjacent to the development site can be made subject to
STW’s conditions and approval. However, to safeguard the water supply to our existing customers and meet
our obligation to maintain a wholesome and safe water supply STW will put in place a Risk & Contingency Plan.
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Self Lay Policy & Addendum
A SLO must request a quote for any infrastructure charge and/or meter charges applicable before submitting a
Form 4. Please allow 28 days for the quote.
A SLO must tell STW information about each property it intends to make a service connection to by sending us
a completed Notification to start connecting service pipes (Form 4). This must be sent to STW 10 days before
starting to make any connections, or 5 working days if a STW Watermark, or equivalent scheme, approved
plumber, has completed the work. STW expect that each quote has been paid for before the SLO sends us the
Form 4.
If a STW Watermark approved plumber, or equivalent Water Industry Scheme (WIAPS), hasn’t laid the service
pipes then STW will need to inspect them before the connection to the mains is completed. An STW inspector
will visit the site and inspect the service pipes against a standard set of criteria. The inspector will then let the
SLO know if the laid service pipes have passed this inspection, or if the inspection fails he’ll tell the SLO what
he needs to do to correct any defects. When there is a failed inspection the SLO will need to request a reinspection.
STW expect the minimum information for each plot to be completed on a Form 4:
1. The STW reference number(s)
2. The plot numbers which are ready for inspection/connection
3. The postal address of each plot
4. The date the plots will be ready for inspection/connection
5. The name/organisation who is going to install the meters
6. Confirmation that service connections have been paid for
7. Confirmation of pipe size
8. Confirmation of meter size to be fitted
9. Confirmation of connection to an on-site or off-site main
STW expects the SLO to send a copy of the Form 4 to the STW Customer Experience Manager.
An incomplete Form 4 will be returned to the SLO and this may delay the delivery of the meter and service
connections.
Service connections cannot be made without our prior approval. Failure to comply with this requirement may
mean that the right to connect subsequent service supply pipes will be refused. Under no circumstances
should new service supply pipes be connected to a main that has not been made live and where written
confirmation of the Depress Sample from STW has not been received. Written confirmation is often sent to
the SLO by email.
Metering
All new properties must be fitted with a water meter by the SLO within 5 days of the service connection to our
network.
All water meters will be supplied and delivered by STW to an agreed location and will be paid for by either the
developer or SLO.
SLOs are expected to fit and commission the water meters at the location agreed on the approved design. If an
SLO fails to install a water meter following a service connection then STW will fit one and recharge the cost to
the SLO.
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Self Lay Policy & Addendum
A SLO must tell STW which meters have been installed at each property by sending us a completed
Notification of competed service pipe connections (Form 5) within 5 days of making a service connection.
STW expect the minimum information for each plot to be completed on a Form 5:
1. The STW reference number
2. The plot numbers that have been connected
3. The date of connection
4. The postal address
5. The occupier’s details, if known
If the SLO has also installed the meter we also expect:
6. The date the meter was installed
7. The meter location
8. The meter size
9. The meter serial number
10. The meter reading
STW expects the SLO to send a copy of the Form 5 to the STW Customer Experience Manager.
An incomplete Form 5 will be returned to the SLO and repeated failure of process will be reported to Lloyd’s
Register.
If we attend site and find that a meter has not been fitted in the stated timescales we will charge for our visit
and subsequent visit to fit the meter.
Site Sign-off
To ensure that all agreed apparatus such as fire hydrants, boundary boxes, meters, values and standpipes have
been laid as designed, a STW Customer Experience Manager will walk the site with the site representative
and/or SLO and complete an Apparatus Sign Off form. STW may invite a representative from the local FRS to
a site sign off.
STW suggest completing the Apparatus Sign Off form before the final surface (e.g. tarmac or blocking paving)
has been laid on site, to make it easier to rectify any problems. This can be a phased approach or a one-off
final site walk at the end of the development.
Self Lay Policy and Process Compliance
We aim to ensure that our processes are efficient and effective for both STW and SLOs, so would encourage
feedback to help us to continually improve and build on our collaborative approach to offering an excellent
service to our developers.
However, where we experience repeated non-compliance of our SLO Policy that has, or could not be resolved
through mutual agreement, we will report these to Lloyd’s Register.
Levels of Service
Water UK has produced a set of standards that developers and others can expect from water companies in
relation to the provision of infrastructure for new developments.
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Self Lay Policy & Addendum
These standards form part of the government’s initiative to publish levels of service for all utility providers.
They cover the performance of water companies in dealing with a broad range of activities which are essential
for housing development and are shown here:
Pre Development Enquiry
Target days
21
Definition
A pre-development report will be sent to the developer
within a period of 21 days commencing either (i) on the
day after receipt of a full application, or (ii) if an
incomplete application and/or no payment has been
received with the application, on the day after all the
required information and payment have been received.
An application is full when all the required information
and any required payment have been received.
A pre-development report includes any necessary
network modelling.
Self Lay Acknowledgment
5
An acknowledgement of the application will be sent
within a period of 5 days commencing on the day after
receipt of the application confirming either that the
application is complete or, if not, requesting the missing
information.
Self Lay Service Connection
28
A quotation will be sent within a period of 28 days
commencing on the day after receipt of a full
application.
An application is full when all the required information
has been received.
Self Lay Design <500 plots
28
A quotation will be sent within a period of 28 days
commencing on the day after receipt of a full
application.
An application is full when all the required information
and any required payment have been received.
A quotation includes the design or design approval, the
amount of the asset payment and any amount to be
paid by the SLO or developer. A draft self lay agreement
is sent with the quotation.
Self Lay Design Over 500 Plots
or off Site Reinforcements /
Engineering Difficulties /
Approved List
42
A quotation will be sent within a period of 42 days
commencing on the day after receipt of a full
application.
An application is full when all the required information
and any required payment have been received.
A quotation includes the design or design approval, the
details of any required network reinforcement or
associated infrastructure, and the amount of the asset
payment and any amount to be paid by the SLO or
developer.
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Self Lay Policy & Addendum
Mains Construction
90
The construction and connection of the water main will
be completed either (i) within a period of 90 days
commencing on the relevant day, or (ii) no later than on
the date agreed with the developer.
The construction and connection of the new water main
is completed when the new water main is under
pressure from the network.
The relevant day is when an undertaking under S42 of
the Water Industry Act 1991 has been signed by the
developer and a valid security has been received.
This service level is applied separately in respect of each
individual phase on a development site.
Service Pipe Connection
21
The service pipe connection will be completed within a
period of 21 days commencing on the relevant day.
The relevant day is the day after all the required
conditions are satisfied (typically all the conditions are
satisfied when the trench & service pipe inspection has
passed.)
Timescales can be extended by agreement with the
customer due to third party need (Schedule 13 WIA /
TMA / Third Party Land)
Water companies are publishing these standards quarterly to demonstrate their commitment to providing
transparency about their performance and to help drive improvements in their levels of service. To see how
STW are performing against these standards see here Water Companies.
Disputes
If there is an issue that is unable to be resolved satisfactorily by the STW Customer Experience Manager then
please escalate to the appropriate escalation point which can be found on our current contact list
In line with Ofwat’s expectations we aim to be fair, clear, transparent and accurate with our dealings with
SLOs. Any queries about our self lay policy or self lay activities can be raised with our Developer Services Team
on 0800 707 6600.
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Self Lay Policy & Addendum
Part 2: Severn Trent Water’s Addendum to the Self-Laying of Water Mains
and Services - A Code of Practice for England and Wales (2nd Edition)
Amendments to the Code of Practice
This Addendum show the changes that STW have made to the Self-Laying of Water Mains and Services - A
Code of Practice for England and Wales (2nd Edition) (Code of Practice) and apply to the construction of new
water mains by self lay organisations (SLO).
Supplementary clauses
The structure and numbering of the clauses follow those in the Code of Practice.
Part 1 – General
1.1 APPLICATION
Insert clause 12
Where an application is made on behalf of the Developer by the SLO, the Developer must give STW written
notification that the SLO is acting as an agent on their behalf. The Developer will need to enter into a Self Lay
Agreement on STW’s standard terms and conditions, together with the SLO and any relevant landowner(s). If
the Developer wants the Asset Value Payment to be paid to the SLO, they must confirm this in writing in the
Acceptance of Proposal.
1.5 COMPETENCE OF SELF LAY ORGANISATIONS
Insert clause 6
In order to demonstrate competence, a SLO must be a member of the Lloyd’s Register Water Industry
Registration Scheme (WIRS) and hold a current approval certificate granting at least partial accreditation
before they can design and/or construct a new water main and service connections within STW’s operational
area.
1.11 FINANCES
Insert clause 8
The following financial terms will apply to a Self Lay Agreement:
a) When the self laid main has been constructed, or part thereof, in accordance with the Self Lay Agreement
and STW then adopts it, STW will pay the developer an Asset Value Payment calculated in accordance with
sections 51A to 51E of the Water Industry Act 1991 (the Act). This Asset Value Payment is the lesser of:
i.
the estimated annual income that STW would receive over a 12 year period from the water charges
from the occupied premises that will be connected to the new water main. This will depend on the
rate at which the development and occupation of the site takes place and
ii.
the annual borrowing costs of a loan, over a 12 year period, of the amount which STW would have
needed to lay the main itself
b) In accordance with the Act, any payment for non contestable works must be paid before STW countersign
and issue the Self Lay Agreement and before construction. This payment is the lesser of the statutory
commuted sum and the cost for STW to provide non contestable works
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Self Lay Policy & Addendum
c) The Asset Value Payment is paid to the nominated party indicated in the Acceptance of Proposal in the Offer
Letter
d) STW’s charges for the self laying of mains and services can be found in our current Developer Charges
booklet which can be found on our website at stwater.co.uk/developers
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Self Lay Policy & Addendum
Part 2 – Self Lay Procedures
2.2 INITIAL ENQUIRY
Replace clause 1
1. The initial enquiry process is shown in Figure 4
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Self Lay Policy & Addendum
Insert clause 7
Before any design work can be started by STW, we’ll need to do a technical appraisal of our network to find
the point of supply and see if any off site work is needed. The point of supply can be determined through a
development enquiry application which is available on our website: stwater.co.uk/developers/applicationforms-and-guidance-notes/
Insert clause 8
Any costs that are provided at this stage are purely indicative and should not be relied upon as an accurate
reflection of the Asset Value Payment that the Developer or SLO may receive.
Insert clause 9
For developments greater than 500 properties, or those likely to use significant water, STW will confirm within
10 days of receiving the application an alternative date for providing the information.
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Self Lay Policy & Addendum
2.3 DESIGN AND APPLICATION
2.3.1 Design by Developer/SLO
Replace clause 1
1. The design process is shown in Figure 5
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Self Lay Policy & Addendum
Insert clause 8
The design shall be in accordance with STW Design Manual and can be requested by emailing
new.connections@severntrent.co.uk
Insert clause9
When the Developer or SLO returns the signed Self Lay Agreement to STW they should provide a material and
fittings list to confirm that all materials and fittings meet both industry and STW requirements
Insert clause 10
Fire Authorities are responsible for the cost of any additional hydrants not shown on the original design that
they specifically request to be incorporated into the design
Insert clause 11
Developers can design a new water mains scheme but they or their designers must be WIRS accredited for
design. STW must approve the design before a Self Lay Agreement can be issued and before any construction
starts. During the design process we’ll need to do a technical appraisal of our network to find the point of
supply and see if any off site work is needed. If not already known, the point of supply can be determined
through a development enquiry application - see 2.2.
Insert clause 12
An accredited designer of a new mains scheme must consult with the Fire Authorities to ensure compliance
with the requirements of the Water Industry Act 1991 and the Fire and Rescue Services Act 2004. The designer
is responsible for liaison with the Fire & Rescue Service (FRS) and for agreeing the provision of water for fire
fighting.
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Self Lay Policy & Addendum
Replace clause 2.3.2 Design by Severn Trent Water
Replace clause 1
1. The design process is shown in Figure 6
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Self Lay Policy & Addendum
2.4 CONSTRUCTION STAGE
2.4.1 Notification of Start
Replace clause 1
1. The construction process is shown in Figure 7
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Self Lay Policy & Addendum
23
Self Lay Policy & Addendum
Replace clause 2
Once the design and details of the work have been agreed and a Self Lay Agreement issued, a pre start
meeting must be held between the Developer, the SLO, a STW Customer Experience Manager, STW’s third
party contractor and any other interested party.
The following actions must be taken:
(i) A minimum of 15 working days notice, either by notice or email, should be given of the proposed start of
the works
(ii) Within this notification period a date needs to be incorporated, giving at least five working days notice
before the start of the works, for the pre start meeting to take place in order to agree the start date and
construction practices and at which point evidence of the contractor’s competencies are to be provided
(iii) No work is to start until the pre start meeting has taken place and all the issues raised have been dealt with
to everyone’s satisfaction. Minutes should be taken.
At this meeting the following must be confirmed:







The competence of the SLO and their construction operatives completing the works
The programme of works, including completion and potential test dates and materials
Details of any routine in-line mains connections the SLO is permitted to carry out
Notification arrangements for the progress of works
Permissions to work in private land, or adopted highway connection arrangements for off site service
connections
Arrangements for service laying payments
Evidence that the Fire & Rescue Service has been consulted on fire hydrant position including a copy
of the Fire & Rescue Service response, unless provided prior to the meeting. Where not available a
date must be agreed to provide the response
Replace clause 3
The Developer/SLO should use STW’s Notification to start constructing a new water main (Form 2) to tell us
that work is to start on site and provide weekly whereabouts for the gangs.
Insert clause 4
Under no circumstances shall any construction work be started until a Self Lay Agreement has been signed, a
pre-start meeting has been attended and STW has provided written confirmation that the construction design
is approved. Failure to do so may result in Lloyd’s Register being notified of non-compliance and the SLO losing
their accreditation.
Insert clause 5
On-site liaison needs to continue throughout the construction stages and the work will be randomly and
routinely audited by a STW Customer Experience Manager. Any non compliance with the specification will
result in the work being stopped until defects are rectified.
Insert clause 6
Once the main is live, or part thereof, and any remedial works notified to the SLO or Developer have been
rectified, STW will issue a Vesting Certificate to formally adopt the mains and on receipt of an invoice from the
SLO or Developer pay the Asset Value Payment.
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Self Lay Policy & Addendum
Insert clause 7
From the date of vesting of the new main in STW, there is a maintenance period of 12 months, during which
time STW can require the SLO to repair any defects. In the event of a default of any of the SLO’s obligations
under the Self Lay Agreement, the Developer will become jointly and severally liable for those obligations.
2.4.2 Water Main Installation
Insert clause 8
Before the final connection is made, the SLO must provide STW with a Fire Hydrant Adoption Certificate which
proves that the requirements of the Fire & Rescue Service have been met.
Insert clause 9
Before the final connection is made, STW will need to confirm that the works have been completed as per
design and as-laid drawings.
Insert clause 10
During construction the SLO should display both normal and emergency contact details.
2.4.3 Final Connection
Insert clause 2
SLOs that have met the Lloyd’s Register WIRS requirements are permitted to complete routine in-line mains
connections. The criteria for a routine in-line mains connection is:


To a newly laid main, either laid by STW as a spur off an existing main or by any SLO at the end of a
previous phase of main laying
To mains which are controlled by a valve, or mains that can be squeezed off without affecting existing
customers, so there is no interruption to supply to existing customers
Insert clause 3
The Developer/SLO should use STW’s Water mains sampling and commissioning notification (Form 3) to tell
us that a final connection is needed.
Insert clause 4
The Developer/SLO should provide the notification of chlorination within 24 hours of it being taken to reduce
the likelihood of failure.
Insert clause 5
The Developer/SLO needs to be aware that it may take up to up to 5 working days from the date any sample is
taken for the pre and post connection sample results to become available.
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Self Lay Policy & Addendum
2.4.4 Service Pipe Installation
Replace clause 1
1. The process for the installation and connection of service supply pipes is shown in Figure 8
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Self Lay Policy & Addendum
Insert clause 9
Whilst STW gives installers the flexibility to programme service connections to suit their own construction
programme, this programme must be agreed with STW to allow us inspect the work when necessary.
Insert clause 10
The construction programme for service connections must be given to STW at least five working days before a
connection is needed and STW must be made aware of any changes to the programme within 48 hours of the
planned connection date.
Insert clause 11
Where STW arrange to inspect the work and find that the activity is not proceeding in accordance with the
agreed programme, our abortive inspection charges will be recharged and the work will be subject to
verification before being accepted.
Insert clause 12
Self lay service connections should meet the installation requirements specified in Table 1 and Section 2.4.4. of
the Code. Contestable activities in the design and construction of water mains and services of the Code are
generally restricted to connections up to and including 63mm nominal bore.
Insert clause 13
During construction, the SLO should ensure adequate courtesy signs are available displaying normal and
emergency contact details for the SLO
Insert clause 14
The Developer/SLO should use STW’s Notification to start connecting service pipes (Form 4) to tell us of that
you’re about to start making service connections. This must be sent to us 10 days before starting to make any
connections, or 5 working days if a water regulations certified plumber has completed the work.
Insert clause 15
The Developer/SLO should use STW’s Notification of completed service pipe connections (Form 5) to tell us
about completed service pipe connections and meter installations. This must be sent to us within 5 days of
making each connection.
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Self Lay Policy & Addendum
Part 3 – Design and Construction Guidance
3.1 GENERAL DESIGN PRINCIPLES
Insert clause 8
When undertaking design the Developer/SLO must ensure that the design of mains and services meets the
requirements of:
 The Code of Practice
 STW’s Addendum to the Code of Practice
 The Self Lay Agreement
 The STW Design Manual
3.2 DESIGN REQUIREMENTS
Insert clause 3
Polyethylene should be the default material for all diameters up to 180mm nominal bore. However, when
ground conditions are not suitable for PE80/PE100 the following products are approved for use within STW’s
operating area:
Size of Pipe
Pipe Material
Mains and services up to 110mm diameter
Puriton, Protectaline
Mains 180mm diameter
Protectaline
Mains 100mm to 300mm diameter
Ductile Iron
Standard sizes acceptable are 63mm, 90mm, 125mm, 180mm PE. All other pipe sizes must have approval
from STW.
3.4 DESIGN GUIDANCE – GENERAL
Replace clause 6
The design should take into account the impact of the works on the environment and the impact of the
environment on pipe installation.
STW’s recommendations for tree and surface planting are:




Poplar and willow trees should not be planted within 10m of the water main
The following trees should not be planted within 6m of any pipe – ash, beech, birch, most conifers,
elm, horse chestnut, lime, oak, sycamore, apple and pear
No shrubs or bushes should be planted within 1m of the centre line of any pipe
The following shallow rooted shrubs/bushes are suitable for screening purposes in close proximity to
water mains – blackthorn, broom, cotoneaster, elder, hazel, laurel, privet, quickthorn, snowberry and
most ornamental flowering shrubs
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Self Lay Policy & Addendum
3.5 DESIGN GUIDANCE MAINS
3.5.1 Mains Design
Insert clause 4
As a general guide, it should be possible to limit the loss of supply to about 50 properties when isolation valves
are closed due to operational or emergency situations.
Insert clause 5
The diagram below shows the preferred locations for the location of values at road junctions, where valves are
required to be installed at road junctions.
Safer Operation of Valves at Junctions
Footway
Carriageway
carriagew
Traditional valve positions
ay
Footway
Carriageway
carriageway
Valve arrangement for safer
operation
29
Self Lay Policy & Addendum
Insert clause 6
Valve operation – closing direction of valves by STW district
1
2
3
8
1
2
3
4
6
7
8
9
10
11
12
13
14
15
30
County
West Shropshire and Montgomeryshire
East Shropshire
Wolverhampton
Birmingham
Worcestershire
Gloucestershire
South Warwickshire
Coventry & North Warwickshire
Leicestershire
Nottinghamshire
Sherwood
North Derbyshire
Derby
Staffordshire
7
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Insert clause 7
Fire hydrants – Full Bore Hydrants are the STW standard and must be used in all new installations. There are
exceptions to the application of this standard where Type 2 Loose Jumper Hydrants should be installed in areas
considered to be at risk of back siphonage resulting in water quality issues. Requirements are detailed in the
STW Design Manual. In built up areas, marker posts will only be provided where requested by the fire service.
Insert clause 8
Pressures within the distribution system are maintained as low as possible but should provide a minimum
pressure of 20m head at the outlet of the stop tap on the boundary for all services.
Insert clause 9
Maximum flow velocity should be 1m/sec. Minimum velocity should be 0.2m/sec achieved at least twice per
24 hour period, not withstanding pipe sizes.
Insert clause 10
Connections should be designed so that once installed there is no need to disrupt the live system again in
order to make the final piece through. Piece up lengths should be kept to less than 5m in length.
Insert clause 11
As a principle, service connections are preferred over rider mains and the design should take account of this
requirement.
3.5.2 Depth of Cover
Replace clause 1
All water mains are to be laid to a minimum cover of 900mm to finished ground surface. The maximum cover
should not be greater than 1200mm.
In addition:
 Consideration should be given if mains will be subject to wheel and point loads, especially from
construction traffic
 In fields which are likely to be ploughed the depth of cover should be 1200mm
 Mains may be laid outside the above specified depths in exceptional circumstances, e.g. geological
conditions or crossing of existing utilities, with the prior agreement, in writing, from STW.
3.6 DESIGN GUIDANCE – SERVICES
3.6.1 Service Design
Insert clause 8
Under normal conditions blue MDPE pipework to BS 6572 must be used. Where the ground is contaminated,
then metal sheathed MDPE must be used. This is standard MDPE pipe factory sheathed with an aluminium
barrier coating protected with an outer layer of blue MDPE incorporating 4 brown identification stripes.
Various sizes are available between 25mm – 110mm nominal bore inclusive.
If copper tube is used as the alternative, it must be to BS 2871 Table Y for underground use and be factory
coated with blue PE. The pipe must bear a BS Certification Mark which states that it has been effectively
cleaned internally.
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Self Lay Policy & Addendum
3.6.3 Sizing of Service Pipes
Replace clause 1
The head loss due to friction should not exceed 1m per 10m head at average flow. The minimum size for
service pipes is 20mm nominal bore.
3.6.4 Multiple Service Connections
Replace clause 4
Where multiple connections, 4 and above, are required, manifolds should be installed.
3.6.5 Meter Boxes
Replace clause 1
All service connections to new properties require a boundary box to be fitted, normally on the edge of the
property boundary to control flows and enable a meter to be fitted. For apartments or flats where a single
incoming service is provided into the building, internal meters shall be fitted to each property in accordance
with STW metering specification.
Replace clause 2
Boundary boxes/stop taps should be situated no more than 300mm from the customer’s boundary. Boundary
boxes to comply with WIS 4-37-01 and shall be rigid Type R. The box shall provide continuously variable height
adjustment up to 150mm. Boxes for installation in normal ground conditions shall be Class 2 and in
contaminated ground shall be Class 1 sealed units with metal union connectors. Screw down covers should
not be installed on the Boundary Box and plastic covers are only acceptable when installed in the footway.
3.7 CONSTRUCTION
Insert clause 8
Joints in PE pipes – The layout of the pipe system should be designed to minimise the number of joints. Butt
fusion joints are the preferred method and electrofusion joints shall only be designed when site specific
circumstances dictate that welding cannot be carried out outside the excavation. The design should allow for
sufficient room to complete the process. If using electrofusion joints, and as per manufacturer’s guidelines, the
mechanical scraping of joints is the preferred option. Hand scraping joints are only acceptable under
exceptional circumstances and must be approved before use by STW.
Insert clause 9
Joints in PE barrier pipes, such as Puriton and Protectaline, can either be mechanical or electrofusion in
accordance with the manufacturer’s recommendation. The appropriate fittings should be used to ensure the
integrity of the pipework.
Insert clause 10
When installing ductile iron fittings to PE mains, joints should be by stub flange thereby maintaining a fully end
loaded system.
32
Self Lay Policy & Addendum
3.7.4 Service Connections to the Water Distribution System
Replace clause 1
The service pipe should be laid at right angles to the main and ferrules.
Replace clause 2
The minimum spacing between tappings, for any material, should be 500mm apart.
Replace clause 3
Service connections to Puriton or Protectaline mains shall only be made using the pipe manufacturer’s self
tapping ferrules designed specifically for use with their own barrier pipe system.
Insert clause 8
In order to protect the integrity of the STW network and maintain a quality water supply to our existing
customers, STW will complete a risk assessment on the connection being made and may insist that a Risk and
Contingency Plan (R&C Plan) is in place before any connection is made to our existing network.
3.7.5 Data Capture/‘As-Laid’ Drawings
Replace clause 12
Prior to being sampled or connected the SLO must provide 3 copies of ‘as laid’ drawings and a fully completed
STW Asset Data form, clearly marked with sampling and connection points along with SLO and Developer’s
name, STW reference number, scheme number, scheme name, scheme type, stage number, date of
completion of the scheme or phase and the date of submission. Where SLO and Severn Trent Water software
is compatible, drawings should be submitted electronically.
33
Self Lay Policy & Addendum
Version control
Version number
Draft v1.0
Date
6 November 2015
Version 1.0
21 December 2015
Version 1.1
6 January 2016
Signed off by
Vicky McGrory Business Change
Manager (STW)
Vicky McGrory Business Change
Manager (STW)
Vicky McGrory Business Change
Manager (STW)
34
Self Lay Policy & Addendum