Ablocked drain can affect several flats, bathrooms or drains in a building at the same time. The most common signs are gurgling noises, unpleasant odours, slow-draining pipes and, in the most serious cases, sewage backing up through toilets, showers or floor drains.
How can you tell if the problem is in the downpipe? One of the most important clues is that the problem affects several outlets connected to the same pipe, particularly on different floors or in different flats. When only one sink, washbasin or shower is affected, the blockage is usually in its individual pipe; when several drains are affected, the blockage may be in the downpipe or in another shared section of the drainage system.
Therefore, before attempting to resolve the problem, it is important to identify where the blockage is and what is causing it. If the blockage is in a shared pipe, it may be necessary to have the pipes professionally unblocked in order to restore the system’s drainage capacity.
What is a downpipe and what is it used for?
A downpipe is a pipe, usually vertical, whose function is to collect and carry water from different floors of a building to the horizontal drainage system.
It can receive water from:
- Toilets.
- Washbasins.
- Showers and baths.
- Sinks.
- Washing machines.
- Other sanitary ware.
- Rainwater drainage systems, where there is a dedicated downpipe for this purpose.
In multi-storey buildings, a single downpipe can serve different flats situated one above the other.
This means that a problem in this pipe system can have very different consequences to those of a blockage confined to a single drain.
How can you tell if a drainpipe is blocked?
It is not always possible to identify a blocked drainpipe simply by looking at a drain. However, there is a combination of signs that can help you spot it.
| Symptom | What it may indicate |
|---|---|
| A single washbasin or sink is draining poorly | Possible blockage in the individual drainpipe |
| Varios sanitarios desaguan lentamente | Posible obstrucción en un tramo común |
| Possible blockage in the drainpipe | |
| Disruption to the flow of air and water in the system | |
| Sale agua por una ducha o sumidero | Posible bloqueo aguas abajo |
| Accumulation of waste or drainage problems | |
| There may be a persistent blockage or a problem with the drainage system |
These symptoms provide an indication of the cause of the problem, but the exact location of the blockage requires an inspection of the system.
Main symptoms of a blocked drainpipe
Several drains are starting to malfunction
It is one of the most important signs.
If a sink in a home stops draining properly, the problem may lie there. But if there are problems with the toilet, shower and other drains at the same time, it is more likely that the blockage is in a shared pipe.
Suspicion grows even further when different flats connected to the same riser show similar signs.
You can hear gurgling sounds
Bubbling or gurgling noises occur when air and water do not flow through the system as normal.
For example, you might hear noises in a nearby shower or washbasin when you flush the toilet.
An isolated gurgling sound is not enough to confirm that a drainpipe is blocked, but when combined with slow drainage or backflow of water, it may indicate a problem with the drainage system.
Water is backing up through the toilet, shower or drain
This is one of the symptoms that requires the swiftest action.
When there is a major blockage, water flowing down from the upper floors may encounter an obstruction and seek another way out.
The lowest points in the plumbing system, such as showers, drains or certain toilets, can then become points where waste water backs up.
Unpleasant odours appear
A partial blockage can lead to the build-up of organic matter inside the downpipe.
Over time, unpleasant odours may develop and spread to bathrooms, kitchens or communal areas.
Unpleasant odours do not always indicate a blockage, as they may also be linked to traps, ventilation or other issues. That is why it is important to consider the full range of symptoms.
The problem particularly affects the lower floors
When a drainpipe is blocked at the bottom, water from the upper floors continues to flow downwards until it reaches the blockage.
This means that the effects are likely to be felt first in homes or premises situated above the blockage point and, in particular, at the lowest-lying healthcare facilities.
A sewage backflow on the ground floor may therefore be a sign of a problem in a shared pipe.
What is the difference between a blocked drain and a blocked downpipe?
This is one of the most important questions for correctly diagnosing the problem.
A localised blockage usually affects a single toilet or drain. A blockage in a downpipe can affect several outlets connected to the same pipe at the same time.
For example:
If only the kitchen sink is draining slowly but the other sanitary fittings are working properly, it makes sense to start by checking the sink’s drain pipe.
On the other hand, if water comes out of the shower when the toilet is flushed, several drains are gurgling, or several flats are experiencing the same problem, there may be a blockage in a shared section of the pipework.
When it is unclear where the problem lies, pinpointing the exact location of the blockage helps to avoid unnecessary interventions and enables direct action to be taken on the affected area.
The most common causes of a blocked drainpipe
Drainpipes can become blocked for various reasons. In some cases, there is a one-off blockage, whilst in others, the internal diameter gradually narrows over a period of months or years.
Wet wipes and hygiene products
Wipes are one type of waste that can cause significant problems in sewerage systems because they do not behave in the same way as conventional toilet paper.
The following may also be withheld:
- Sanitary towels.
- Tampons.
- Cotton buds.
- Nappies.
- Cotton.
- Plastics.
- Large quantities of paper.
These materials can become caught on uneven sections of the pipe and start to trap other debris.
In our article on the materials that commonly cause blockages in pipes, we explain in more detail which items you should avoid flushing down the drain.
Fats and organic waste
Grease from kitchens can cool down and gradually build up on the inside of the pipes.
As the deposited layer thickens, other debris adheres to it and the effective diameter of the pipe is reduced.
In buildings containing several flats, restaurants or hospitality premises connected to the mains supply, this problem can lead to significant build-up.
Limescale, sediment and deposits
Mineral deposits and other sediments can gradually reduce the cross-sectional area available for water flow.
The problem can be particularly significant when combined with old pipework, damaged internal surfaces or a build-up of other debris.
Debris from building works or renovations
Following a renovation, materials that should never end up in a drainpipe may accidentally find their way into the drainage system.
Residues of cement, plaster, mortar, paint or other products may harden or become stuck to the pipework.
When the blockage is caused by hardened material, conventional cleaning may not be sufficient, and it is necessary to assess the appropriate technique for removing it.
Old or damaged pipes
Not all blockages are caused solely by waste.
Old pipes may show signs of corrosion, roughness, deformation, cracks or changes to their internal cross-section.
These irregularities make it easier for waste to become trapped.
Therefore, if a drainpipe repeatedly becomes blocked in the same place, it is worth checking whether the problem is actually caused by dirt or by the condition of the pipe itself. The article on the maintenance of old pipes explores in detail the problems associated with ageing pipes.
A break or bend in the downpipe
A damaged downpipe may lose its original shape and create areas where debris becomes trapped.
In such situations, temporarily allowing the water to flow does not necessarily resolve the root cause of the problem.
If the blockage reoccurs at the same point after several clearances, it is advisable to assess the structural condition of the pipe.
How do you unblock a drainpipe?
The procedure depends on the diameter of the pipe, the location of the blockage, the pipe material and the type of debris that has built up.
In a professional repair, the aim should be to restore the flow of water and establish why the blockage has occurred, particularly when it is a recurring problem.
1. Identify which areas are affected
First, they check which toilets, homes or floors are causing problems.
This helps to determine whether it is an individual blockage or a common pipe.
For example, knowing which is the highest and which is the lowest property affected can provide useful information for narrowing down the area where the blockage is located.
2. Locate the blocked section
The point where the water appears does not always coincide with the location of the blockage.
A return pipe for a shower on the ground floor may originate several metres further on.
Therefore, correctly pinpointing the fault before taking action prevents work being carried out on sections that are operating normally.
3. Clean the pipework
Where there is a build-up of grease, sludge, sediment or other debris, professional equipment can be used to dislodge and flush away the material.
Cleaning pipes with pressurised water enables the removal of accumulated debris from the interior and restores the pipe’s clear bore when the characteristics of the installation allow this technique to be used.
The aim is not simply to make a small hole in the plug so that water can flow through again, but to remove the build-up that is preventing the water from draining away.
4. Check the downpipe if the problem recurs
If a drainpipe becomes blocked again after it has been cleared, you need to ask yourself why.
The following may exist:
- A distortion.
- A break.
- A misaligned joint.
- A persistent build-up.
- A trapped object.
- An internal narrowing.
- A fault in another section of the network.
An inspection of the inside of the pipes using a camera allows the condition of the pipework to be visually checked and any defects that may be causing blockages to be identified.
5. Assess the need for repairs if there is structural damage
If the inspection confirms that the downpipe has cracks, breaks or other damage, continuing to clear blockages on a regular basis may not be the right solution.
Depending on the type and condition of the pipework, non-invasive pipe repairs may be considered to refurbish certain sections without having to carry out traditional work involving the breaking up of walls or paving.
Can you unblock a drainpipe yourself?
It is not advisable to tamper with a communal drainpipe without knowing the location and nature of the blockage.
Home remedies that can be used for minor blockages in a washbasin or sink are not the same as dealing with a drainpipe that carries waste water from several households.
Furthermore, using unsuitable tools or large quantities of chemicals may:
- Failing to reach the actual point of the blockage.
- Shift the problem to another section.
- Damage to dilapidated pipes.
- Pose risks when handling waste water.
- To complicate the procedure at a later stage.
In fact, there are several common mistakes people make when trying to unblock pipes themselves, which can end up making a problem that was initially quite straightforward much worse.
What should you do if you suspect that the drainpipe is blocked?
If you notice several of the above symptoms, you should follow these steps:
- Temporarily reduce your water usage. If there is a significant blockage, continuing to flush water from upper floors may increase the risk of backflow or overflow.
- Check whether it affects more than one sanitary fitting. This helps to distinguish between an individual blockage and one located in a shared pipe.
- Ask whether other properties have the same problem. In a housing estate, this information can be very useful in determining which downpipe is affected.
- Do not use chemicals indiscriminately, especially if you do not know the material, age or condition of the pipework.
- Request an inspection if there is a sewage backflow or if the problem is recurring. In such cases, it is advisable to locate and diagnose the fault before it causes further damage.
What happens if a drainpipe isn’t unblocked?
A partial blockage may start with nothing more than a slight gurgling sound or a slower bowel movement than usual.
However, if material continues to build up, the diameter available for the water may gradually decrease until a much more serious blockage occurs.
Possible consequences include:
- Wastewater return.
- Flooding in bathrooms or ground-floor premises.
- Unpleasant odours.
- Overflows.
- Damp.
- Damage to walls, ceilings or cladding.
- Problems between different properties within a housing estate.
- Temporary suspension of the use of toilets and kitchens.
The Ministry for Ecological Transition and the Demographic Challenge notes, with regard to the maintenance of sewerage networks, that blockages may be caused by sediment build-up, breaks and cracks, roots or foreign objects, and distinguishes between preventive maintenance and corrective measures in the event of an incident.
Although a building’s downpipe is a much more specific installation than a public sewerage network, the principle is the same: when a blockage recurs, understanding the condition of the pipe and the cause of the build-up enables a better decision to be made on how to resolve the issue.
Who is responsible for clearing a blocked drainpipe in a housing estate?
Before deciding who should be responsible for carrying out repairs, it is necessary to identify which section is affected and whether it forms part of a communal or private installation.
It should not be assumed that any blockage found inside a property belongs exclusively to that property.
If the source is a shared downpipe, the problem may affect various owners connected to that pipe.
That is precisely why, when community issues arise, it is important to technically pinpoint the affected area before determining who is responsible.
For shared installations, as well as taking action when a fault occurs, it may be useful to carry out regular maintenance on the communal pipework to check areas that are particularly prone to the build-up of debris.
How to prevent blockages in downpipes
Not all traffic jams can be prevented, particularly where there is structural deterioration, but good practices do reduce the risk.
Do not flush wipes or hygiene products down the toilet
Although certain products are marketed as flushable, minimising the amount of solid material entering the drainage system reduces the risk of blockages.
Avoid spilling oils and fats
Cooking oil and fats must be disposed of properly and must not be poured down the sink.
Once inside the network, they can adhere to the walls and contribute to the formation of deposits.
Keep an eye out for the early symptoms
Gurgling noises, unpleasant odours or increasingly slow bowel movements should not be ignored if they occur repeatedly.
Taking action whilst the blockage is still partial can prevent a complete blockage.
Review recurring issues
Unblocking a drainpipe several times in the same place without investigating the cause is not always the best strategy.
If the problem recurs, it is advisable to check the internal condition of the pipework.
Scheduling maintenance in buildings with recurring issues
Communities, hotels, holiday apartments, restaurants and buildings subject to heavy use may require more frequent inspections.
In such cases, pipework maintenance contracts enable preventative inspections and cleaning to be scheduled according to the characteristics and history of each installation.
When is it urgent to take action on a blocked drainpipe?
It is advisable to request prompt intervention when:
- Wastewater is coming out of a shower, toilet or drain.
- Several homes have been affected.
- The ground floor is starting to show signs of wear and tear.
- The water level continues to rise.
- There is a risk of flooding.
- Bathrooms and kitchens cannot be used as normal.
- Leaks or damp patches appear.
- The traffic jam has occurred repeatedly at the same spot.
In such situations, continuing to use water from other plants may make the problem worse.
Unblocking downpipes in the Marina Alta and La Safor
At Limpiezas Domingo, we have over 15 years’ experience in work relating to pipework and sewerage networks. We operate in the Marina Alta and La Safor regions, serving homes, owners’ associations, housing estates, businesses and other premises.
We operate in towns such as Dénia, Xàbia/Jávea, Gata de Gorgos, Benissa, Teulada-Moraira, Calpe, Oliva, Gandía and nearby towns.
In the event of a blocked drain, the work may involve locating the affected area, clearing the pipe and, where blockages are recurrent, inspecting the inside of the pipe.
The key is not simply to get the water flowing again, but to determine why the blockage occurred and whether there are any circumstances that could cause it to happen again.
Frequently asked questions about blocked drainpipes
How can you tell if the drainpipe is blocked?
A drainpipe may be blocked when several toilets or properties connected to the same pipe are experiencing problems at the same time. Gurgling noises, slow drainage, unpleasant odours and water backing up from showers or drains are some of the most common signs.
How can I tell if the blockage is in my pipe or in the downpipe?
If only one toilet is affected, the blockage is usually in its individual branch pipe. If several drains, different rooms or several flats on the same riser are affected, there is a greater likelihood that the problem lies in the downpipe or another shared section.
Why does a drainpipe get blocked?
Causes may include a build-up of grease, wipes and hygiene products, solid debris, sediment, limescale, foreign objects, construction debris or structural problems with the pipe itself.
What should you do if a drainpipe is blocked?
It is advisable to reduce water usage, check which areas and properties are affected, and locate the section where the blockage is situated. If there is a backflow of sewage or if several areas are affected, it is advisable to seek professional assistance.
How do you clear a blocked drainpipe?
The procedure depends on the type of blockage and the layout of the system. Specialised drain-clearing equipment and high-pressure cleaning systems may be used. If the problem recurs, it may be necessary to inspect the inside of the downpipe using a camera.
Why does a drainpipe get blocked again after it has been cleared?
Dirt may be stuck inside, or there may be a structural issue, such as a deformation, break, narrowing or irregularity where debris accumulates again. In such cases, it is advisable to investigate the root cause of the problem rather than simply clearing the blockage again.
Can a blocked drainpipe cause water to leak from the shower?
Yes. If there is a blockage further down the pipe, the water can back up and come out of the lowest points connected to the system, such as showers, drains or certain toilets.
Can a blocked drainpipe affect several neighbours?
Yes. A single downpipe can carry waste water from several flats on different floors. A blockage in a shared section can affect more than one owner.
Is it necessary to carry out building work to locate a blockage in a drainpipe?
Not necessarily. There are camera-based location and inspection systems that allow the interior of pipes to be examined and faults to be pinpointed without having to start construction work straight away.
When should a downpipe be inspected using a CCTV camera?
It is particularly recommended when the blockage recurs, its exact location is unknown, there is a suspicion of a break or deformation, or cleaning has not permanently resolved the problem.