Unblock sewer yourself: with high pressure or a spring

First: is the blockage really in the sewer?

If only one drain is running slowly, the problem is almost always in the trap or the first section of pipe. You don't need drain rods for that; see blocked kitchen drain or blocked shower drain. If several drains are running poorly at the same time, the toilet is gurgling or water is coming up from the lowest drain point, the blockage is probably in the sewer.

Where does my sewer run, and how deep is it?

In most homes, all drainage comes together in the soil stack, runs under the floor (often through the crawl space) to the outside and connects to the municipal sewer, usually at the street side. Along the way there is often an access point: a section of pipe with a screw cap or clamp lid. You'll find this in the crawl space, at the front of the house, in the garden under a paving slab or in an inspection chamber.

Don't know where your sewer runs? Check the building plans of your home. These can often be requested from the building archive of the municipality. In terraced houses the sewer is usually in a similar location at the neighbours'.

The sewer lies frost-free in the ground and runs at a gradient towards the street, so it usually gets deeper towards the property boundary. Exactly how deep varies per property. If you're digging, bear in mind cables and pipes in the ground. For excavation work with a machine, a KLIC notification is mandatory; even for manual work it's wise to know in advance what's there.

Unblock sewer with a snake

A drain snake is a flexible coil that you feed through the pipe while rotating. A hand snake reaches a few metres; for the sewer, an electric snake is often hired.

1. Put on gloves and safety goggles and lay down plastic sheeting or old cloths.
2. Open the access point. If the pipe is full, water may come out: keep a bucket ready.
3. Insert the spring whilst turning, always in the same direction (usually clockwise). If you turn back, the spring can come loose or get tangled.
4. If you feel resistance, keep turning gently without pushing hard. A spring that you force can kink or jam.
5. Pull the snake back whilst turning, clean it and flush thoroughly with plenty of water.
6. Close the access point properly again; otherwise sewer gas will escape.

If you are using an electric drain snake, first read the instructions and keep hands, loose clothing and jewellery away from rotating parts. Never use a snake directly in a toilet bowl without a protective sleeve: it will damage the porcelain.

Unblock sewer yourself with high pressure

For some high-pressure cleaners an unblocking hose is available: a long hose with a spray head that sprays backwards and thus pulls itself into the pipe. With this you can spray loose soft blockages and light grease deposits. However, a domestic high-pressure cleaner cannot be compared with professional equipment, and there are clear risks:

• Dirty water and splashes. Sewer water contains pathogens. Wear goggles and gloves and wash your hands thoroughly afterwards.
• Damage to the pipe. Older, brittle or subsided pipes can be further damaged by the pressure.
• Water in the house. If you spray into a blocked pipe, water can come up from the lowest drain or the toilet. Have someone inside keep watch.
• A hose that whips back. Only turn on the pressure once the head is well into the pipe, and turn it off before you pull the hose out.
• Electricity. Use a socket with RCD protection and keep plugs and extension leads dry.
• Never combine with chemical products.

When do you stop?

• The spring or hose gets stuck or won't go any further.
• You hit something hard or feel roots.
• The water still doesn't drain after a few attempts.
• The blockage has come back several times recently.

In those cases there is often more going on, such as subsidence, a break or root ingress. Read more about a subsided sewer or roots in the sewer. If you want to know what the price of professional unblocking depends on, read what does sewer unblocking cost?