Asbestos in drain pipes: how do you recognise an asbestos cement pipe?

Drain pipes can contain asbestos if they are made of asbestos cement. Waste, underground and rainwater pipes made of asbestos cement were laid before asbestos was banned (2005 at the latest across the EU, and earlier in many countries), both inside buildings and in the ground on the property. Cast iron and plastic pipes are not asbestos cement, but their joints and coatings may contain other materials. A grey asbestos cement pipe cannot be reliably told apart from a concrete or fibre cement pipe with the naked eye, so only a sample analysed in a laboratory gives you certainty.

This article deals with the drain pipe itself: where asbestos cement pipes are found, how to tell the pipe materials apart, which work affects the pipe and how to take a sample from the pipe. You can read about pipe insulation on the page Asbestos in pipe insulation.

Where are asbestos cement drain pipes found?

Asbestos cement pipes do not rust and tolerate moisture well, so they were used in many kinds of drainage. Asbestos cement pipes may, for example, be found in the following places:

• soil stacks and their branches in walls or ducts by the bathroom and kitchen
• underground drains under the floor slab and in the basement floor
• house connection pipes and rainwater pipes in the ground on the property
• vent pipes of the drainage system that pass through the roof
• pipe sections fitted during older repairs into a run otherwise made of another material

Several pipe materials can occur in the same building. The soil stack may be cast iron, the underground drain asbestos cement and the house connection plastic, or the other way round. That is why each section to be removed is assessed on its own.

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

Appearance gives clues but no 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 that of a concrete pipe. A magnet does not stick.
• Cast iron: dark, often rusty and heavy. A magnet sticks, so cast iron is easy to tell apart from the others with a magnet.
• Concrete: thick wall, rough surface, and aggregate is visible on a broken edge.
• 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 decide what a grey, non-magnetic pipe is made of. A CCTV drain inspection does not reliably show whether the pipe is asbestos cement either. If a grey pipe is to be cut, removed or worked on from the inside, it is worth taking a sample of it.

Joints and coatings are different materials

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 the joints are to be removed, it is worth testing the seal or compound of the joint as a separate sample.

Which work affects the drain pipe?

An intact pipe that stays in place does not release fibres. Fibres can be released when the pipe wall is broken, cut or ground. For drainage, such work includes, for example:

• cutting and removing pipes during a pipe replacement or bathroom renovation
• connecting a new pipe to an old one, when the old pipe is cut
• pipe relining, in which the pipe is often mechanically cleaned and milled on the inside before the new lining is installed
• replacing the house connection pipe, when an excavator or spade hits the pipe in the ground
• repairing a defective pipe, in which the damaged section is replaced

It is worth establishing the pipe material before you hire a contractor, because it affects the working method and who is allowed to do the work.

Where on the drain pipe do you take the sample?

• The best place is a pipe end that has already been cut or opened, a damaged edge or a pipe exposed during digging.
• Do not take a sample from a pipe in use in a way that weakens the wall or makes the pipe leak. An old pipe can be brittle.
• Take a separate sample from each pipe section that differs, for example from the soil stack, underground drain and house connection separately.
• If the pipe run has been repaired, a replaced section may be made of a different material from the rest of the run.

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 pipe is contaminated with 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 take the sample. Wipe a dirty outer surface and then lightly moisten the sampling spot with a spray bottle.
3. Use pliers to nip off a small piece of about 2–5 centimetres from the edge of the open pipe end. Alternatively, you can use a chisel to remove a thin shaving from the outside. Do not saw, drill or grind.
4. If the pipe is painted or coated, take the piece together with the coating.
5. Put the piece straight into a resealable plastic bag, seal it and place it in a second bag.
6. Label the bag with the sampling location, for example "Basement, underground 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 take a sample of the seal or compound of a joint, put it in its own bag and label it separately. You will find more advice in the articles How to take an asbestos sample and How to pack an asbestos sample.

What does the result mean for the drain pipe?

Semlab analyses the sample with a JEOL SEM-EDS electron microscope in accordance with ISO 22262-1, and you receive the result by email in English, usually on the same day the sample arrives at the laboratory. The result shows whether asbestos was detected in the sample you sent.

• No asbestos detected: the result applies to the pipe section tested and to identical pipes. Other sections, such as the house connection or repaired sections, are tested separately.
• Asbestos detected: cutting, removing and internal milling of the pipe are planned as asbestos work under the occupational safety rules, and the demolition is carried out by a contractor specialising in asbestos removal. An intact pipe can also stay in place as long as it is not damaged. A removed pipe is asbestos waste; how to deal with it is described in the article Disposing of asbestos waste.

If the drainage is part of a larger pipe replacement or demolition that requires an on-site asbestos survey, a qualified surveyor carries out the survey on site. Semlab is a laboratory and does not carry out on-site surveys.

How much does analysing a drain pipe cost?

The analysis costs €49.99 incl. VAT per sample, and the price is the same for 1–100 samples. For orders of more than 100 samples we can make a separate arrangement. Postage is not included in the price. You can order the analysis online, pay by card and send the sample as a letter or small parcel with your national postal service to the laboratory in Finland.