Sewer connection methods: If you want to make a connection to a public sewer, legally you must give the Statutory Undertaker or Water Authority notice, complete the forms, and pay a fee. We advise planning your work to allow adequate time for the 21-day notice period. At Premier Drainage Solutions, we can handle all the paperwork for you and deal with Water Authorities on your behalf.
Key to the application process is knowing which sewer connection method you are proposing to undertake. This article explores the different sewer connection methods available. If in any doubt, contact us and we’ll be happy to advise you on sewer connections.
Different sewer connections:
- Pre-formed junctions.
- Oblique (Y-Piece) junctions.
- Square drainage junctions.
- Brick sewers.
- Existing manholes.
- New inspection chamber.
- New manhole.
- Pre-formed saddle.
- Adoptable connections (laterals).
Oblique and square pre-formed junctions can be used for sewer connections. It is good practice to have a boundary manhole no more than 1 metre into the boundary, to give good rodding or jetting access to the connection if required.
Oblique (Y-Piece) junctions
Connections to the public sewer should generally be made using oblique junctions. A junction is inserted into the line of the public sewer after a section of the existing pipework has been cut out and removed. Jointing is by means of a repair coupling at each side of the junction pipe.
Guidelines state that “For oblique junctions, make the connection at 9 to 3 o’clock angle but never below the expected diurnal flow height of the main channel.” This is so a branch line can enter the main line at an angle of 45 degrees, ensuring the flow from the branch enters the flow of the main line at pace, without causing disruption or backwash.
Any connection from a toilet or soil vent pipe should be made using an oblique junction, and it is generally good practice to use them on all connections if possible.
Square drainage junctions
Also known as curved square junctions, square drainage junctions have the branch line entering at 90 or 87 ½ degrees. They are suitable for storm system connections, and also used for rodding points, backdrops prior to chambers, and dip pipes on septic tanks.
Connection to public brick sewers (including flat slab tops)
Water Authority guidance states that, “The orifice for the new connection should be made by carefully core drilling or removing bricks from the side of the sewer, preferably within the top third. Where applicable, the top slab may be temporarily taken off to aid this process. The connection should not be made by attempting to core drill the top slab.”
Connection to existing public manholes
This is not a preferred method of connection as the existing manhole may not be able to accommodate the new connection. If the manhole is suitable, the new pipe must be connected in such a manner that the soffit levels of the existing and new pipes are the same. Where the existing manhole has a preformed invert, then the invert of the connection should be formed and made good in granolithic concrete as required. Pipes in manholes should never be plastic.
Connection to public sewer via new inspection chamber
This is only permitted up to a depth of 2m and not in public highways. Polypropylene inspection chambers or rectangular pre-cast concrete inspection chambers in accordance with an approved list of manufacturers may be used. Concrete surround should be used in inspection chambers where they are subject to vehicle loading e.g. driveways. For depths in excess of 1.2m a restricted access opening of 350mm diameter would need to be used. Inspection chamber covers must be made from ductile iron.
Connection to public sewer via a new manhole
This is primarily for larger drainage schemes. Manholes must be pre-cast concrete rings that adhere to ‘Sewers for Adoption’ 7th edition specification. Manhole covers have to be ductile iron and carry the appropriate strength for the area where they are situated.
Connection to public sewer pipe via pre-formed saddle
The use of saddles to clay or concrete sewers is acceptable where the public sewer diameter is three increments larger than the connection diameter, e.g. a 300mm dia. public sewer can only be connected to by a 100mm dia fitting. Saddle connections must be positioned at 10 o’clock or 2 o’clock and at an angle of 45 degrees to the direction of flow. A single hole in the Public Sewer must be made by diamond core drilling. Saddles shall be the same material as the existing public sewer.
Adoptable connections (laterals)
An adoptable lateral is an accessible single length of drain or sewer not greater than 150mm diameter from a property to a public sewer on adjacent land or highway. A demarcation chamber should be positioned at the head of the lateral at a position 1m inside the property boundary. Rising (pumping) mains are not acceptable as adoptable laterals. Hatch boxes are not acceptable as demarcation chambers.
Regardless of which sewer connection methods you are planning, you should always use an experienced and certified drainage professional to advise you. At Premier Drainage Solutions we can help with everything from filing in your Section 106 application to making good after connecting to a public sewer. Our 40+ years of experience means your project runs on budget and on time.
Get in touch now and we’ll be happy to help.