Asbestos in drain pipes: how to recognise an asbestos cement pipe

Drain and sewer pipes can contain asbestos if they are made of asbestos cement. Asbestos cement drain, underfloor drain and stormwater pipes were installed before 1994, both inside buildings and underground on private plots. Cast iron and plastic pipes are not asbestos cement, but their joints and coatings can be made of other materials. A grey asbestos cement pipe cannot be reliably told apart from a concrete or fibre-cement pipe by eye, so certainty comes from a sample analysed in a laboratory.

This article focuses on the drain pipe itself: where asbestos cement drains are found, how to tell pipe materials apart, which jobs affect the pipe and how to take a sample from it. Asbestos cement as a material is covered in the article asbestos cement, and pipe insulation on the page asbestos in pipe insulation.

Where are asbestos cement drain pipes found?

Asbestos cement pipe does not rust and copes well with moisture, so it was used in many kinds of drains. Asbestos cement pipes may turn up, for example, in these places:

• soil stacks and their branches, inside bathroom and kitchen walls or in service ducts
• underfloor drains beneath the ground floor and in basement floors
• private sewers and stormwater drains buried in the yard
• drain vent pipes that rise through the roof
• short sections replaced during earlier repairs in a line otherwise made of another material

One building can have several pipe materials. The stack may be cast iron, the underfloor drain asbestos cement and the yard sewer plastic, or the other way round. That is why every section to be removed is assessed on its own.

How do you tell an asbestos cement pipe from other pipes?

Appearance gives clues but not certainty. This is how the pipe materials usually differ:

• Asbestos cement: grey, hard, cement-like surface that may be painted. The wall is usually thinner than in a concrete pipe. A magnet does not stick.
• Cast iron: dark, often rusty and heavy. A magnet sticks, so cast iron is easy to pick out with a magnet.
• Concrete: thick wall and coarse surface, with aggregate visible in a broken edge. More on concrete in the article asbestos in concrete.
• Plastic: light, often grey, white or orange-brown. A plastic pipe is not an asbestos product.

A magnet is a good first test, but it does not settle what a grey, non-magnetic pipe is made of. A drain camera survey does not reliably show whether a pipe is asbestos cement either. If a grey pipe is going to be cut, removed or treated from the inside, it is worth taking a sample.

Joints and coatings are a different material

The joints of cast iron and plastic pipes may contain seals, tapes or compounds, and the pipe surface may have a bitumen-like coating. These are different materials from the pipe itself. If joints are being taken apart, it is worth testing the joint seal or compound as a sample of its own.

Which jobs affect a drain pipe?

An intact pipe left in place does not release fibres. Fibres can come loose when the pipe wall is broken, cut or ground. In drains this includes, for example:

• cutting and removing pipes during a full pipe renovation or a bathroom renovation
• connecting a new pipe to an old one, when the old pipe is cut
• relining and pipe coating, where the pipe is often cleaned and mechanically milled from the inside before the new lining goes in
• replacing a yard sewer, when an excavator or spade hits the buried pipe
• repairing a broken pipe, where the damaged section is replaced

It is worth identifying the pipe material before choosing a contractor, because it affects the working method and who is allowed to do the work. Other asbestos materials in a pipe renovation, such as tile adhesives and fillers, are covered in the article asbestos in a pipe renovation.

Where on the drain pipe should the sample be taken?

• The best spot is a pipe end that has already been cut or opened, a broken edge, or a pipe exposed in an excavation.
• Do not sample a pipe in use in a way that weakens the wall or makes it leak. An old pipe can be brittle.
• Take a separate sample from each different section, for example the stack, the underfloor drain and the yard sewer.
• If the line has been repaired, a replaced section may be a different material from the rest.

How to take a sample from a drain pipe

1. Wear disposable gloves and a respirator of at least class FFP3. The inside of a drain carries waste water and bacteria, so do not touch it with bare hands and wash your hands afterwards.
2. Make sure no water runs into the open pipe while you work. Wipe a dirty outer surface and then lightly mist the sampling spot with a spray bottle.
3. With pliers, nip a small piece of about 2–5 centimetres off the edge of the open pipe end. Alternatively, chip a thin flake off the outer surface with a chisel. Do not saw, drill or grind.
4. If the pipe is painted or coated, take the piece with the coating on.
5. Drop the piece straight into a zip-lock bag, seal it and put it inside a second bag.
6. Mark the bag with the sample location, for example "basement, underfloor drain by the laundry room, grey pipe".
7. Cover the sampling spot with tape and wipe the area with a damp cloth.

If you also sample a joint seal or compound, put it in its own bag and label it separately. More instructions are in the articles how to take an asbestos sample and how to pack an asbestos sample.

What does the result for a drain pipe mean?

Onelab analyses the sample with a JEOL SEM-EDS electron microscope in accordance with ISO 22262-1, and the result is sent by email, typically on the day the sample arrives. The result tells you whether asbestos was detected in the sample you sent.

• No asbestos detected: the result applies to the section tested and to identical pipe. Other sections, such as the yard sewer or replaced pieces, are tested separately.
• Asbestos detected: cutting, removing and milling the pipe from the inside are planned as asbestos work, and the removal is carried out by a company authorised for asbestos removal work. An intact pipe can also stay in place as long as it is not broken. Removed pipe is asbestos waste, and its handling is covered in the article asbestos waste disposal.

If the drains are part of a larger pipe renovation or demolition that requires an on-site asbestos survey, the survey is carried out on site by a qualified surveyor. Onelab is a laboratory, and on-site surveys are handled by our sister brand AsbestiPro.

How much does the analysis of a drain pipe sample cost?

The analysis costs €39.90 + VAT per sample, and the price is the same for 1–100 samples. Orders of more than 100 samples can be priced separately. Postage is not included. You can order the analysis online and send the sample to the laboratory by post.