What is 3-D drain scanning?

A three-dimensional scan of a drain pipe or chamber. 3-D scanning can be carried out using an optical camera system or with a laser. The optical system creates a high-resolution image of the inside of a chamber. Both systems map the shape and dimensions of chambers and pipes, with a very high degree of accuracy.

What is ambient cure resin?

A resin used when repairing drains with lining systems. This resin cures in ambient temperature.

What are culverts?

Channels, either aboveground or underground, that take water past other features, such as roads, railways, buildings and other water courses. Culverts are also used to channel subterranean water courses.

Bathroom gully (BG)

A bathroom gully is a type of drain that channels water from showers, baths and sinks in a bathroom or shower room. It contains a trap that holds water. This is designed to stop noxious sewer smells from entering the home. A bathroom gully can be easily accessed from outside the property to remove blockages.

What is cured in place pipe (CIPP)?

A ‘no-dig’ pipe rehabilitation solution for drains that creates a new pipe inside the existing pipe. It is often the quickest, least disruptive and most sustainable way to repair damaged pipes. CIPP lining is especially useful when a pipe cannot be excavated.

Confined space entry (CSE)

Confined space entry is a process of entering a chamber or large pipe to inspect, clean or repair it. This is a hazardous process, particularly in sewer systems, due to the potential presence of potentially deadly gasses plus the risk of slips, trips and falls or head injuries from striking the structure.
Operatives are expected to follow strict health and safety procedures when carrying out confined space entries.

These include:

  • Having multiple personal ready to support and rescue operatives who get into difficulty.
  • Using special equipment to assist in entering a chamber, such as a tripod access system.
  • Wearing and use of special personal protective equipment (PPE), including gas monitors and emergency respirators.

All operatives carrying out confined space entries should have passed specialist training. In particularly hazardous cases, a dedicated confined space rescue team, using full breathing apparatus and with advanced first aid training, must be in place to support operatives carrying out a confined space entry.
These conditions make drainage work that requires confined space entry more time consuming and more costly. Reputable drainage specialists always consider how to carry out work using remote access solutions before they carry out confined space entries to eliminate risks.

What is a drain?

A pipeline, which conveys foul sewage and/or surface water, runoff from a single property.  It is usually of small internal diameter.

What is a drain dye test?

A drain investigation technique that involves introducing a non-toxic powdered dye into the drain system. By monitoring the flow of the coloured water, pipe connections and blockage problems can be identified.

What is drain excavation?

Digging down into the ground to access blocked pipes. This technique is often only used as a last resort due to the disruption it causes and the potential to cost more.

What is drain jetting?

The use of powerful water jets to clean pipes and chambers and remove blockages.

What is drain rodding?

Blockages are removed using flexible poles called drain rods. Poles can become stuck in pipes during drain rodding so the technique should only be used by experts.

Drainage sump (DS)

A drainage sump is pit built into a pipe system that collects debris, silt and other materials to prevent it from causing blockages. Sumps are often associated with pumping systems that remove water from basement areas in properties or channel wastewater from low-lying pipes to ones at higher levels in the sewer system. Sumps need to be emptied and cleaned regularly to ensure they work effectively.

What is a drain survey?

The process of examining a drain to assess its construction, connectivity, and condition.

What is drain tracing?

Drain tracing equipment is used to identify the precise location of a pipe underground. An example is a CAT and sonde. A sonde is a radio transmitter, usually attached to CCTV camera survey equipment which can be detected above ground by the CAT, a radio receiver.

What is electro-mechanical pipe cleaning?

Where it is unsafe to use water jetting, an electro-mechanical pipe cleaning device can be used to break through blockage material. This method is often used to clean soil pipes and downpipes in buildings.

What does FOG stand for?

FOG stands for fats, oil and grease. FOG can build up in drains and sewers leading from kitchens, restaurants and food factories, causing serious blockages. It is a key component of fatbergs.

What is a pipe liner?

A pipe liner can be used to repair a long section of sewer or downpipe using the CIPP process. These are often referred to as ‘full liners’ to distinguish them from shorter liners which are called local structural repairs, patch liners, or point liners.

What is hot water and steam CIPP?

A cured in place pipe (CIPP) lining system that uses hot water or steam to cure the resin impregnated in a liner. Water is poured into the pipe under pressure and heated to around 95 degrees centigrade to cure (harden) the liner. The technique is often used to install liners in culverts and larger pipes. A disadvantage of hot water CIPP lining is that it creates large volumes of water contaminated with styrene that leaches from the resin. This needs to be contained and taken for safe disposal at a specialist waste site.

Inspection chamber (IC)

Inspection chambers are access points to underground pipework, commonly associated with managing wastewater. They are commonly placed where different pipes meet, at points where there are bends in pipes and at intervals along long straight pipe runs. This assists with the maintenance of pipes, for example through carrying out CCTV surveys or removing blockages. Inspection chambers are often narrower and shallower than manholes. This means they allow visual inspection of key points in pipe systems and the use of drainage survey camera systems, but not person entry into the chamber.

What is a jet vac tanker?

A specialist tanker that has both a water jetting system for cleaning pipes and a vacuumation system for sucking up wastewater so it can be taken away for disposal or pumped into another pipe system.

Kitchen gully (KG)

A kitchen gully is a type of drain that channels wastewater from sinks, washing machines and dishwashers located in kitchens and utility rooms into a foul drain. It contains a water trap designed to stop noxious sewer smells from entering the home. This can be easily accessed from outside the property to remove blockages.

Manhole (MH)

Manholes are openings to a confined space asset, such as a shaft leading to an underground pipe or culvert, or to a chamber, tank or a sump pit. They are designed to be large enough to allow a person to enter the asset. Manholes are secured with the fitting of a manhole cover or manhole lid, usually made from steel. Manholes can also be referred to as sewer access points, which are secured with access covers or access lids.

What are no dig repairs and sewer repairs?

Drain repairs that can be carried out remotely without having to excavate a pipe.  No-dig repair systems are therefore often the least costly and disruptive, and the most sustainable way to repair pipes.

What are patch liners?

Patch liners are short liners made up of tubes of glass reinforced plastic (GRP) or felt – usually up to 1.5m long – impregnated with resin that are used to rehabilitate pipes with faults in discreet locations. The liners are created by folding sheets of GRP and layers of resin. The material is then wrapped around a packer and installed in the pipe with a flexible rod or pulled through with a rope. Once the patch liner is at the repair location, the packer is inflated, pushing the liner against the pipe. The liner is then left to cure in ambient temperature. Patch liners are also called local structural repairs and point liners. They are used to repair cracks and other faults, strengthen pipes and smooth pipes, for example where joints are displaced, to reduce the risk of waste material snagging on sharp edges.

What is a pushrod drain survey camera?

A CCTV drainage survey camera system used to inspect smaller diameter drains. A mini video camera and powerful LED light is located on the end of a long, flexible rod that can be pushed along a pipe. Pushrod cameras are used to survey pipes with diameters up to 150mm. The flexible rod is stored on a reel called a camera reel, which can be up to 200m long. An advantage of a pushrod CCTV camera is that it can be directed around sharp bends in a pipe. It is also portable so can be used in remote locations and throughout buildings.

What is a robotic CCTV survey camera?

A remotely controlled drainage survey camera that is attached to a wheeled carriage, powered via an electric cable. Robotic camera systems, also called crawler cameras, are used for surveying pipes with diameters from 150mm up to 1600mm. The camera head can be controlled and moved by the CCTV drainage engineer to get the best view of the inside of a pipe.

What is robotic cutting?

A technique that uses remotely controlled mechanical devices to remove blockage material or modify pipework. Robotic cutters are powered hydraulically or by electricity. They can be used to remove roots, concrete, scale and objects that are protruding into pipes. The latter can include stakes and concrete piles that have been inadvertently driven into sewers. They can also be used to remove protruding pipework that creates snagging risks. Robotic cutters usually use grinders rather than bladed cutters.

Rodding point / Rodding eye (RP)

Rodding points are narrow access points into a drainage system to allow pipes to be inspected using a pushrod camera system, have blockages removed, or be cleaned as part of planned maintenance. They get their names from flexible drainage rods that can be guided into pipes to clear blockage material. They also provide access for water jetting hoses. Rodding points are located at critical points in drainage systems where blockages are most likely to occur. They are also known as rodding eyes.

What is sewage?

Wastewater that contains human waste.

What is a sewer?

A pipeline, which normally conveys foul sewage and/or surface water runoff from more than one property.

Soakaway (SAW)

A soakaway is a water management system for the controlled dispersal of surface water into the ground. It is installed where ground may otherwise become boggy in gardens or public areas.
In its simplest form, a soakaway is created by digging a large hole and filling it with rubble or gravel, sometimes held in wire cages. These underground structures hold rainwater, which can then soak more slowly into surrounding soil. Modern versions use modular plastic boxes, similar to milk crates. These provide structure, yet are lightweight, while proving more storage space for water.
A soakaways can also be made up from a system of perforated plastic pipes. These are often called herringbone soakaways due to the way they are laid in a V-shaped pattern extending across the area of ground that needs to be drained.

Soil vent pipe (SVP)

A soil vent pipe is a pipe that rises from a property’s sewerage pipe to a point above the wet area of a pipe system. Most can be seen to rise to a point above the roof eaves.
Soil vent pipes have two practical purposes. They vent noxious gases and smells from the sewer system away from properties. They also equalise the pressure inside drains. This prevents u-bends in toilets and other systems from emptying through the siphoning effect, where a reduction in pressure draws down water in the sewer.
Soil vent pipes can be inside or outside walls. Many older ones were made from cast iron. Most soil vent pipes in new homes are usually located on external walls and are made from plastic.

Surface water gully (SWG)

A surface water is a type of drain that is dedicated to dispersing rain water that falls on and around a property into the surface water drainage system. A common design is the bottle gully that has a trap at the bottom that collects silt and debris before it can get into a surface drain. Surface water gullies are used to drain water from paved areas and from roofs via downpipes. They have openings protected by grids so can be accessed from outside the property to remove debris and blockages.

What is ultraviolet light (UV) CIPP lining?

A cured in place pipe (CIPP) lining system that uses UV light to trigger catalysers in resin which is then cured (hardened) to create a new pipe within a pipe. The UV light is delivered by a flexible wheeled light train holding a series of powerful UV light bulbs that is pulled through the liner after it has been inflated with compressed air at a predetermined speed to optimise the curing process. UV pipe lining is often faster, more sustainable and less disruptive than hot water CIPP (see above) because it requires a smaller work area, curing times are faster and it generates no contaminated wastewater.

What are vaccumation tankers?

A specialist vehicle with a large tank and a vacuumation system used to remove and transport wastewater. Vacuumation tankers are often used to clear flood water or redirect it into sewers or nearby water courses – or to take it to authorised disposal sites.

Water downpipe (WD)

A downpipe is a commonly a vertical pipe that channels water from a property’s gutter system into surface water gullies at ground level where it then enters the surface water drainage system. In older properties, downpipes may be embedded in walls and are commonly made from cast iron. In most modern properties, they are attached to external walls, for ease of maintenance, and are made from plastic.


A cesspit is a tank, buried underground, used to hold wastewater generated by a property. The wastewater is not treated. It is collected at regular intervals for disposal at an authorised site.


Another name for a cesspit (see above).

Drainage field

A drainage field, also known as a soakaway field, is a system of pipes used to safely drain effluent (liquid waste from a septic tank or sewage treatment plan) into the ground.

Inspection chamber

Inspection chambers are used to gain access to pipework, for example underground sewer pipes.

Off-mains drainage

Drainage systems that are not connected to the main public sewerage system, and are therefore not serviced or maintained by water companies.

Septic tank

A septic tank is a buried tank that collects sewage from a property. The wastewater is subjected to moderate treatment by undergoing a settlement and separation process combined with simple anaerobic digestion. Effluent can then be discharged into a drainage field (see above) if allowed under general binding rules. Remaining waste must be regularly collected for authorised disposal.

Sewage treatment plants

Also known as package treatment plants, sewage treatment plants combine a wastewater settlement and separation process with a more sophisticated and more thorough bio-treatment process than with a septic tank. The effluent water is therefore cleaner. Effluent can then be discharged into a drainage field (see above) or watercourse if allowed under general binding rules. Remaining waste must be regularly collected for authorised disposal. 

Soakaway field

Another name for a drainage field (see above).

Wastewater pipe

A wastewater pipe carries sewage from a property to the cesspit, septic tank or sewage treatment plant.

Communication pipe

The water service pipe that carries water from the water main to the property boundary. The water company is responsible for maintaining this pipe.

Internal stop tap

A tap located inside a building for turning on and off the flow of clean water.

Leak detection

The process of looking for and locating a leak in a water system. There are different techniques for carrying out leak detection, depending on the location of the leak, its spread and the scale of the damage it has caused.

External stop tap

A tap located outside a building that controls the flow of water from the communication pipe along the supply pipe and into the property. The external stop tap is owned by the water company.

Pipe tracing

Water pipe tracing is used to locate the precise position of pipework underground and within a building. Pipe tracing can be essential to locate and fix a water leak, carry out other maintenance on the water supply system or allow other maintenance work to be carried out on or near the building.

Point water pipe repair

The process of repairing a pipe in one discreet location. It may involve having to excavate the pipe. The repair may involve replacing a section of pipe or fitting a specialist clamp over the hole causing the leak.

Supply pipe

The pipe that carries the water from the communication pipe into the property. The property owner is responsible for the maintenance of the supply pipe.

Water pipe moling

A method used to replace all or part of a water pipe. Compressed air is used to force a moling head through soil. A new water pipe can then be inserted into the created underground channel.

Water pipe re-routing

This method involves altering the direction of part or all of the existing water supply pipe.  This method is primarily used when the leak is difficult or impossible to access and/or the existing water supply pipe is likely to incur further leaks due to its current location.

Water pipe replacement

Where a water pipe has seriously deteriorated or is made of material that is no longer suitable, the water pipe can be replaced.

Water quality testing

Water quality testing is carried out to ensure a property’s water supply meets required standards and is safe to use. Water testing may be needed if there are concerns about contamination of drinking water supplies or of hot water systems.

Water service pipe

A water service pipe is the pipe that takes water from the water main to a property. It is made up of the communication pipe and the supply pipe.

Arboricultural report

An arboriculturist report shows how trees, which are located nearby, can increase subsidence risks or cause real damage to properties.

Borehole investigations

A hole drilled into the ground around a structure to assess ground conditions and take samples for laboratory testing. Borehole investigations may form an important part of subsidence investigations to assess how the condition of soil and other substrates are affecting subsidence risks.

Crack and level monitoring

A process of monitoring the crack development and level movement across a property.

Laboratory root testing

The scientific testing of tree and plant roots to assess if they have contributed to, or may contribute to, subsidence or other structural damage.

Laboratory soil testing

The scientific testing of soil and other material samples to identify physical and chemical properties that influence subsidence risks.

Mackintosh probe in-situ testing

A technique used to identify the variability of soil structures at different depths.

Shear vane test

A test to measure the undrained shear strength of cohesive soil. This helps assess the likelihood of a soil breaking down, resulting in increased subsidence risks.


A vertical downward movement of a building foundation caused by the loss of support beneath it. Subsidence can occur suddenly or gradually.

Trial hole / Trial pit investigations

A technique used to assess the condition and material types in structure foundations. The opening of a trial hole allows key foundation measurements to be taken both to assess risks and plan remedial action if it is needed.

Acoustic profiling

A technique used to identify the noise created by an underground water leak. Microphones and digital acoustic software allow engineers to assess the location and severity of the water leak.

Correlation leak detection

Detectors are placed around the location of a suspected leak. By analysing (correlating) the frequencies of the sound of the escaping water from these locations, the location of the leak can be pinpointed.

Damp meter detection

A damp meter, also called a moisture meter, can be used to detect and assess the levels of moisture in walls, floors and ceilings. This data helps locate the leak, assess its severity, the scope of the damage caused, and the actions needed to both stop the leak and repair the damage.

Dye leak detection

Water engineers place a non-toxic water-soluble dye in a water system and monitor the way it flows through pipes, and potentially out of them, to help locate pipe and tank leaks and other faults, such as faulty valves.

Flood water

A body of uncontrolled water that has commonly: overflowed from a water course, lake or reservoir; not been able to drain away during or after a period of heavy rain; or has escaped from a drainage pipe, culvert, or clean water supply pipe.

Inspection cameras

A camera system with a mini video camera and a powerful light on a flexible rod that can be used to look into pipes and other hard-to-reach locations. Inspection cameras can be used to find the sources of leaks, determine the scale of leaks or assess other maintenance issues.

Non-destructive leak detection

A range of inspection methods used to locate the source of water leaks without damaging walls, floors, or ceilings or having to excavate underground pipes.

Thermal imaging

Thermal imaging cameras, also called thermography cameras, are used increasingly to locate water leaks by detecting changes in temperature in walls, ceilings, and floors. The camera uses infrared light to to detect temperature differences that cannot be seen by the naked eye. Water leaks will usually show up as colder patches.

Tracer gas analysis

A technique that uses a lighter-than-air gas to detect leaks. Gas is introduced into a water pipe. Highly sensitive gas sensors are placed above the suspected leak. When the bubbles of gas escape from the hole causing the leak, it is detected by the sensors. The gas used is hydrogen, combined safely with inert nitrogen.

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