How to clear a badly blocked pipe when nothing else works

What you need

• 5 or 10 m hand drain auger with a crank handle (Rothenberger Rospi or Wolfpack, 15-35 euros at Leroy Merlin or Bricodepot)
• 10 litre bucket, cloth and long rubber gloves
• Pipe wrench or adjustable pliers for the trap
• Crowbar or hook to lift the inspection chamber lid
• Torch
• Pressure washer with a 7.5 or 15 m drain cleaning kit (Kärcher, 25-40 euros for the kit) if you have one
• Safety glasses
• Concentrated washing-up liquid and hot water
• Set of 32 and 40 mm trap seals in case they get damaged on removal (Jimten or Wirquin, 1-2 euros)
• Heavy-duty rubbish bags for the sludge from the chamber
• New PVC inspection chamber lid if the old one is broken (10-25 euros)

Step by step

1. 1

   Find the section

   Open every tap in the house for a minute and see which drains run and which do not. Flush the toilet and watch the shower. That tells you whether it is local, the branch pipe or the chamber (see the list above). Turn off the supply to any fittings that are overflowing.

2. 2

   Go in at the point nearest the blockage

   For a local or branch pipe blockage, remove the trap of the highest affected fitting with the bucket underneath and work through the wall pipe. For a blockage in the chamber, skip to step 5.

3. 3

   Feed the auger in turning, without pushing

   Feed the auger into the wall pipe and advance it by turning the crank clockwise. When you feel resistance, keep turning without pushing until the auger moves forward on its own. If it jams and does not advance within a minute, do not force it: pull back.

4. 4

   Withdraw the auger and clean up

   Pull the auger out slowly, wiping it with the cloth: it brings out grease, hair or roots that tell you what was there. Refit the trap, run the hot tap for 3-5 minutes with washing-up liquid and check it drains fast.

5. 5

   Open the inspection chamber (ground floors and villas)

   Find the chamber in the patio, the garden or the garage, lift the lid with the crowbar and, wearing gloves, scoop the sludge and solids into the bags with a bucket. Look at where the water comes in and where it goes out: the pipe that is full and not moving is the blocked one.

6. 6

   Auger or pressure washer from the chamber

   Run the auger into the blocked pipe from the chamber, turning as you go. If you have a pressure washer with a drain hose, push the nozzle 50 cm into the pipe before switching on the pressure: the rear-facing jets pull the hose along and strip the grease and limescale. Glasses on.

7. 7

   Flush and check the whole house

   Open all the taps again and flush the toilet several times. Everything should drain in 5-10 seconds with no gurgling and no water rising. If any fitting is still bad, there is something in that section the auger cannot remove: call for the machine and the camera.

8. 8

   Close the chamber and note the date

   Refit the lid clean and, if it is broken, replace it with a new one so roots and soil cannot get in. Write down the date: in villas with trees, the chamber needs cleaning once a year.

How to work out where the blockage is before you start clearing pipes

A domestic drainage system has four levels: the trap under each fitting, the 32-50 mm pipe from the trap to the branch, the horizontal 50-110 mm branch pipe collecting several fittings, and the vertical downpipe or, on ground floors and in villas, the inspection chamber and the buried main run out to the sewer. The lower down the blockage is, the more fittings it affects and the less anything you do from the kitchen sink achieves.

The practical rule: a single drain that is slow or stopped is a local blockage, in the trap or its wall pipe, and is dealt with by an auger from that point. Two or more drains in the same bathroom or kitchen failing together, or water rising in the shower when you flush the toilet, is the branch pipe, and you have to go in with a long auger or a machine from the highest fitting. The whole property slow, smells from every trap, or water welling up through the lowest drain (a ground floor shower, the patio gully) is the inspection chamber or the main run: you have to open the chamber and work from there.

In a block of flats, if water comes up your kitchen sink when the neighbour above empties theirs, the blockage is in the communal downpipe, not in your pipework. That is handled by the comunidad de vecinos (the residents' association); we can diagnose it with a camera, but communal downpipes and septic tanks needing a tanker are done through a partner tanker company.

• Kitchen and utility fail together: kitchen branch pipe, grease. Auger or machine from the kitchen sink.
• Shower, basin and toilet fail together: bathroom branch pipe or the bote sifónico (the shared floor trap). Machine from the floor trap or the toilet.
• Everything fails and smells: inspection chamber or main run. Open the chamber, clean it out and auger towards the sewer.
• Fails when the neighbour uses water: communal downpipe. Residents' association and tanker company.

Mistakes when clearing a badly blocked pipe

The first is stacking products. A caustic gel, then vinegar and baking soda, then another gel from a different brand, and finally bleach. None of it reaches a blockage 3 metres away, and the mixture produces heat and gases in the trap. When we open a trap after that combination, out comes a hot paste that burns. One product at most, and if it does not work, no more chemicals.

The second is caustic soda in flakes or pearls, sold in droguerías. It reacts with water at over 80 degrees, softens PVC, wrecks the joints and, in the lead pipes of older buildings in the centre of Valencia or Alicante, eats right through them. A 110 euro unblocking turns into a new section of pipe at 300-600 euros. Do not use it at home.

The third is ramming the hand auger in. A 6 mm auger from the ferretería (hardware shop) punches through the plug of grease, the water drains for a day and the blockage is back the next, because all it did was make a hole. And if you force it round a bend, it coils up on itself and stays inside: retrieving a stuck auger costs more than the unblocking. Turn without pushing, and if it does not advance, stop.

When to call a professional and what we do

Call when the hand auger gets stuck 2-3 metres in, when two or more drains fail at once, when water comes up through the lowest drain, when the blockage returns within weeks, or when you cannot find the inspection chamber. We go in with an electric drain machine (Rothenberger or Ridgid, with 10-16 mm cables and cutting heads) that strips grease and roots off the pipe wall instead of just boring through them, and with an inspection camera to see what is there: grease, limescale, a break, a back-fall or a lump of rubble that fell into the pipe during a refit.

Unblocking with the drain machine costs 110-180 euros including the call-out, and the camera inspection 60-120 euros, free if you book the unblocking. At night or on a public holiday, 130-220 euros. If the camera shows a broken or crushed section, we give a fixed quote to replace that section. Prices in how much drain unblocking costs, service in drain unblocking. We arrive in 20-45 minutes in Valencia, Alicante, Torrevieja and Benidorm.

Local pages with arrival times: drain unblocking in Valencia, in Alicante, in Elche and in Orihuela Costa.

Coastal pipes: limescale, roots and second homes

The three causes of deep blockages we see most on the Costa Blanca have nothing to do with what goes down the kitchen sink. The first is limescale: at 40-50 French degrees of hardness, in 15 years a 50 mm pipe has 10 mm of crust on its wall, and any trace of grease clings to it. The second is roots: ficus, palms and oleanders from gardens and pavements get in through the joints of the buried main runs at villas in Torrevieja, Orihuela Costa, Jávea or Dénia, and within a year they close the pipe. Only a machine with a cutting head removes them.

The third is homes shut up for half the year. The water in the traps evaporates, the grease and soap dry out and set like plaster, and when summer comes nothing drains. Before closing up the house: two litres of hot water with washing-up liquid down every drain and a spoonful of cooking oil in each trap to slow evaporation. And in villas with an inspection chamber, opening it once a year and scooping out the sludge with a bucket prevents 80 per cent of the call-outs.

Related guides

Before getting this far, you have normally been through how to unblock a kitchen sink or how to unblock a toilet. If you want to know why the home remedy did not work, read baking soda and vinegar for blocked drains.