Fats should never be poured down the sink as they solidify in
the sewers. Disposable nappies and sanitary towels can
easily block a sewer and should not be put down the w.c.
DRAINAGE
If you heed the above advice the likelihood of a blockage
occurring in any drain or sewer is significantly reduced.
If you do suffer a blockage, Thames Water holds records of
all public sewers and, given the location of the blockage,
should be able to advise you whether it is their
responsibility or not. Their telephone number is 0845
9200800.
If it’s not their responsibility, then more than likely it will be
your responsibility and you may have to engage the
services of a specialist company to clear the blockage.
They can normally be found in the “Yellow Pages” under
“Drains and Pipes”.
If there is flooding on the highway due to a blocked gully,
you should, in the first instance, report it to Herts Highways
on 01438 737320.
Sewers can also be blocked by tree roots or can collapse due to
traffic loading. You will need expert help to resolve these types
of problems. Such help can be very expensive and several firms
should be approached for estimates before engaging a firm to
carry out the remedial works. It is appropriate in instances such
as these to commission a close-circuit television (CCTV) survey
to assist in determining the cause of blockages and to help
determine what remedial works are required.
Information provided by: Environmental Services Unit,
Stevenage Borough Council
Tel No. 01438 242242
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INFORMATION SHEET
The following information may assist in clarifying responsibilities
for sewers/drain maintenance: 1.
What is a drainage system?
Generally, a drainage system comprises a separate system
for surface water (i.e. “clean” water from roofs, roads, paths
etc) and foul water (toilet, bath, washbasin & sink waste
water). There are, in the main, four categories of
drain/sewer: 
Highway sewers (surface water only)
A highway sewer is a sewer which drains the highway
only and is owned and maintained by the Highway
Authority namely Herts Highways (Hertfordshire County
Council). A highway sewer will eventually connect into a
public sewer. Within a road there will be a series of road
gullies that collect the rainwater before it then discharges
into the highway sewer. Herts Highways will regularly
clean the gullies but very often they can become blocked
in between regular cleanses and need to be cleared on
an ad-hoc basis.

Public sewers (surface water and foul)
A public sewer is a sewer, which is owned and
maintained by the sewerage undertaker (in Stevenage, it
is Thames Water Utilities Ltd), and not Stevenage
Borough Council. These sewers tend to be the main
sewers, which carry wastewater from residential,
commercial and business properties.
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
Private shared sewers (communal sewers) (surface
water and foul)
A private shared sewer (communal sewer) is a sewer
into which a number of properties are connected but
which is not a public sewer owned by Thames Water. In
this case, all property owners connected to the sewer are
responsible for its maintenance and repair. The cost of
any maintenance/repair would then be the shared liability
(in equal shares) of the owners of all the connected
properties, including the Council, if it owned any of the
properties involved. That liability applies to the whole
length of sewer up to the point it joins a public sewer
owned by Thames Water.

Single private drains (surface water and foul)
A single private drain is usually the connection from a
single property (e.g. from the kitchen waste gully or soil &
vent pipe or the rainwater pipe) to the point it joins either
the public sewer or a private shared sewer.
2.
3.
Who is responsible for communal or shared sewers?
In many instances, individual house drains may be
connected to a shared or communal sewer, which then
connects into the public sewer. In these instances the
maintenance and repair of a communal sewer is the shared
responsibility of the owners of all the properties that
discharge into it. The deeds of your property will probably
indicate that you are responsible for any drain/sewer, which
serves your property. This responsibility extends to any
drain or sewer up to the point that it connects into a public
sewer even if this is beyond the boundary of your property.
A private drain or a shared/communal sewer may extend
under a public highway or even through other gardens not
in your ownership. It is, therefore, important for you to
establish where the public sewer nearest to your property is
situated and at what point your drains connect into it so that
you can ascertain the extent of your responsibility. If no
drainage plans are available, this information can only be
accurately determined by a site investigation.
Who is responsible for the sewers and drains?
The public sewers are owned by Thames Water Utilities
and it is their responsibility to maintain these sewers and to
clear any blockages that might occur. However, it is likely to
be the householder’s responsibility to maintain and clear
any blockages in the drain connection between the house
and the public foul sewer.
A plan showing the public sewers in the vicinity of your
property can be viewed at the Planning Division of the
Council at Daneshill House. However, such plans have
been provided by Thames Water Utilities and the Council
cannot guarantee their accuracy. You can also get
information on public sewers by contacting Thames Water
Utilities’ customer centre on 0845 9200800.
There is no readily available information relating to any
private individual house connections (drains).
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Usually, when a problem such as a blockage occurs in a
shared or communal sewer only one householder may be
directly affected and that householder will probably incur
the expense of rectifying the problem. However, if you are
partly responsible for the maintenance and repair of that
communal sewer you may also be liable for contributing
towards the cost of any remedial work carried out.
4. What causes problems in sewers and drains?
Very few problems occur in surface water sewers.
Blockages occur mostly in foul drains/sewers and can occur
for all sorts of reasons.
One of the most common causes of blockages is foodstuff,
such as tealeaves, rice and hot fats, which enter the
drainage system.
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