A blocked manhole can cause unpleasant odours, slow drainage, noises in the pipes and even the backflow of sewage into a home, business premises or block of flats. Although the problem sometimes starts off as a minor issue, a blockage at this point in the sewerage network can end up affecting several connected pipes.
How can you tell if a drain chamber is blocked? The most common signs are a build-up of water or waste inside the drain chamber, slow drainage from several toilets at the same time, persistent foul odours and, in the most serious cases, overflowing or water backing up through the drains.
When these symptoms appear, it is important to determine exactly where the blockage is and what is causing it. In some cases, a simple clean-out will suffice, whilst in others it will be necessary to use professional drain-unblocking and pipe-cleaning techniques to fully restore the drainage system’s flow capacity.
What is a manhole and what is its purpose?
A manhole is an inspection chamber located within a sewerage network. Its purpose is to facilitate the connection between different pipes and to allow access to specific points in the system for inspection, cleaning or maintenance work.
In a residential property, a residents’ association, a business or an industrial facility, there may be several manholes distributed throughout the network.
Precisely because they are points where different pipes converge, manholes can also become areas where waste accumulates or where a blockage in a nearby pipe becomes visible.
Therefore, finding a manhole filled with water does not necessarily mean that the blockage is inside it. The problem may lie in the outlet pipe, in a sewer further down the line, or even in another section of the system.
How can you tell if a manhole is blocked?
There are several symptoms that may indicate a blockage in the drain or in one of the pipes connected to it.
Water is pooling in the drain
One of the most obvious signs is to open the drain and check that the water level is abnormally high or that it is not going down.
If water enters the manhole but does not drain away as normal, there may be a blockage in the pipe beyond it.
Several drains are draining slowly
should normally start by looking for the blockage in that branch pipe.
However, if several toilets or drains start to drain slowly at the same time, the problem may lie in a shared part of the system, such as a main pipe or a manhole.
Unpleasant odours appear
The build-up of waste water and organic matter can cause unpleasant odours around the drain cover or even allow these odours to enter the home via the drains.
There’s a gurgling sound coming from the pipes
Bubbling or gurgling noises may occur when water and air have difficulty flowing through the pipework.
On their own, these signs do not indicate where the fault lies, but if they are accompanied by slow drainage or water pooling in the drain, it is advisable to have the system checked.
The water flows back through the drains
Water backing up from a shower, toilet, drain or other drainage point is a sign that requires special attention.
This may mean that the water can no longer find a suitable outlet and is flowing back towards lower points in the system.
The drain is overflowing
If water starts to spill out of the manhole cover or floods patios, gardens or garages, the drainage system may have lost much of its capacity to carry off water. In such a situation, it is advisable to minimise water consumption and call out an emergency drain-clearing service before further damage occurs.
Principales causas de una arqueta atascada
A drain can become blocked for various reasons. Identifying the cause is important to prevent the problem from recurring after the system has been cleared.
Accumulation of fat and waste products
Grease from cooking can gradually build up on the inside of pipes. Food scraps and other debris become trapped on these layers, gradually reducing the diameter available for water to flow through.
These are not the only items capable of causing a blockage. Wipes, building debris, toiletries and other materials can also cause problems, as we explain in our article on the types of waste that commonly cause blockages in pipes.
Wipes and products that do not break down
Wet wipes, hygiene products, plastics and other solid waste can travel through the pipes until they become trapped at bends, junctions or in areas with reduced flow capacity.
Over time, they can form large blockages that prevent water from flowing normally.
Sediment, soil and sand
Pipes that carry water from courtyards, terraces, garages or outdoor areas can accumulate sand, soil and sediment.
When these materials settle at the bottom of the pipes, the cross-sectional area available for water flow gradually decreases.
Roots inside the pipes
In underground cables located near trees or landscaped areas, roots can penetrate through joints, cracks or other vulnerable points.
Once inside the pipe, they can trap debris and cause increasingly frequent blockages. When this problem is detected, it is not enough simply to remove the accumulated dirt: it may also be necessary to remove the roots that have grown into the pipes in order to properly restore the inside of the pipe.Roturas, desplazamientos o deformaciones
A recurring blockage is not always caused solely by dirt.
A pipe that is broken, bent, sunken or has a displaced joint can create a point where waste gets trapped time and time again.
In such cases, removing the blockage may temporarily restore the flow, but unless the structural cause is rectified, the blockage is likely to recur.Una arqueta desconocida u oculta
In older homes, renovated properties or gardens where the paving has been replaced, it may be the case that a manhole has been buried and there is no clear information about its location.
When this happens, digging at random is not the best option. There are specific systems for detecting hidden manholes that enable you to locate the manhole before breaking up the road surface.¿Cómo se desatasca una arqueta?
The solution will depend on the location and type of blockage.
In a professional repair, the aim should not simply be to get the water to drain away again, but to locate the problem, clear the blockage and check that the drainage system is functioning correctly once more.1. Check the condition of the manhole
First, the water level, the amount of accumulated waste and the inlet and outlet pipes are checked.
The behaviour of the water can provide clues as to where the blockage is located.
2. Identify where the bottleneck is
The spot where the water pools does not always coincide with the place where the blockage has formed.
When it is not possible to locate the problem visually, equipment can be used to pinpoint blockages and breaks accurately. Knowing where the problem is allows work to be carried out only on the affected section and avoids unnecessary work.
3. Dispose of waste
Depending on the type of blockage, vacuum equipment, mechanical systems or pressurised water may be used.
Where there are large build-ups of grease, sludge or sediment, cleaning pipes with pressurised water helps to dislodge the debris adhering to the inner walls and restore the pipe’s effective diameter.
4. Check the inside of the pipes
If the blockage is a recurring problem or there are signs of a structural issue, it may be advisable to inspect the pipework from the inside.
Pipe inspection using a camera allows cracks, breaks, deformations, tree roots or build-up of debris to be identified without having to break up floors or walls to find out what is going on
5. Check that the network is working properly
Once the blockage has been cleared, you should check that water is flowing correctly through the connected pipes again.
This check is particularly important where there have been repeated traffic jams in the past.
Can you unblock a drain yourself?
If there is only some visible and accessible debris on the surface, external dirt may be removed provided that this can be done without entering the manhole or handling hazardous items.
However, it is not advisable to enter manholes, wells or sewerage systems, or to attempt to clear deep blockages using makeshift methods.
It is also not advisable to overuse harsh chemicals. As well as failing to clear certain solid blockages or resolve structural problems, some products may damage certain materials in the system.
If the drain pit is full, the water isn’t draining away, there is sewage, the problem affects several drains, or the blockage returns after it has been cleared, it is best to have a professional assessment carried out.
What happens if a blocked manhole isn’t cleared?
Allowing the problem to go on unchecked may lead to:
- Sewage overflows.
- Persistent unpleasant odours.
- Slow drainage at various points.
- Backflow of water through toilets or drains.
- Leaks and damp.
- Flooding in low-lying areas.
- New traffic jams at other points around the site.
- Damage to pipes if there is a pre-existing break or structural defect.
Blockages do not always have a single cause. The Ministry for Ecological Transition and the Demographic Challenge, as part of its guidance on the management and maintenance of sewerage systems, considers factors such as sediment build-up, roots, foreign objects and damage to pipes, and emphasises the importance of combining inspection, maintenance and cleaning.
Therefore, when a drain becomes blocked repeatedly, simply removing the blockage may not be enough unless the cause of the blockage is first identified.
How to prevent a drain from becoming blocked again
Once the problem has been resolved, there are a few steps you can take to help reduce the likelihood of it happening again.
Do not use the toilet or drains as a bin
Avoid disposing of wet wipes, toiletries, plastic, food waste and any other waste that is not intended to be flushed down the toilet.
Do not pour oil or grease into it
Oils and fats can stick to the inside walls of pipes and subsequently encourage the build-up of other debris.
Keep an eye on the outdoor drains
In courtyards, terraces and garages, it is advisable to prevent large quantities of leaves, sand or soil from getting into the drains.
Taking action at the first signs
A drain that is draining less and less effectively, recurring unpleasant odours, or a manhole where the water level is starting to look abnormal can be early signs of a problem.
Detecting it before a complete blockage occurs usually makes treatment easier.
Carry out maintenance on facilities with recurring problems
In residents’ associations, housing estates, restaurants, hotels and other properties where the sewerage system is used intensively, waiting for a blockage to occur is not always the most efficient strategy.
In such cases, carrying out regular maintenance on the pipesmakes it possible to schedule cleaning and inspections designed to detect problems before they cause a major blockage.¿Cuándo hay que llamar a un profesional?
When should you call in a professional?
It is advisable to seek specialist help when:
- The sump is completely full and the water level isn’t going down.
- The water is spilling over the lid.
- Several drains are affected at the same time.
- Water is backing up through the toilet, shower or drains.
- The traffic jam keeps happening.
- There are roots inside the pipes.
- A break or deformation is suspected.
- The location of all the manholes is unknown.
- There are persistent unpleasant odours even after cleaning.
- We need to identify the exact location of the blockage.
Particularly in the case of recurring blockages, it is important to distinguish between clearing a one-off blockage and addressing the underlying cause that is causing the blockage to recur.
Unblocking manholes in the Marina Alta and La Safor
At Limpiezas Domingo, we have experience in the cleaning, inspection and maintenance of drainage systems in homes, housing estates, businesses and commercial premises.
We provide our services in the municipalities of the Marina Alta and La Safor regions, including Dénia, Xàbia/Jávea, Gata de Gorgos, Benissa, Teulada-Moraira, Calpe, Oliva, Gandía and other nearby towns.
Depending on the nature of the problem, we can combine different diagnostic and cleaning techniques to determine why the drain is blocked and tackle the root cause of the problem, particularly in the case of a recurring blockage.
Frequently asked questions about blocked manholes
How can you tell if a manhole is blocked?
The most common signs are water pooling inside the manhole, slow drainage from several drains, foul odours, gurgling noises, sewage backflow or overflowing through the manhole cover. If water enters but cannot drain away normally, there may be a blockage further down the pipe.
Why does a manhole fill with water?
It may become blocked because the outlet pipe is blocked by grease, wipes, sediment, roots or other debris. It may also be due to a break, deformation or structural problem that hinders the drainage of water.
Is it normal for a manhole to contain water?
It depends on the type of drain and the installation. The important thing is to check for an abnormally high water level, standing water that does not drain away, or a rise in the water level when the drains are used.
How do you clear a blocked manhole?
The method used depends on the cause of the problem. Suction systems, high-pressure water jets or other professional equipment may be used. If the blockage recurs, it is advisable to inspect the pipes to identify the cause.
Why does a drain become blocked again after it has been cleared?
If the blockage reoccurs, there may be a cause that was not resolved during the first clearance, such as stubborn build-up, roots, a deformed pipe, a break, an incorrect gradient or a problem in another section of the network.
Can a blocked drain cause water to come out of the toilet?
Yes. When a blockage prevents sewage from flowing through the network, the water can back up and come out at low points in the system, such as toilets, showers or drains.
Do you have to break up the floor to find a manhole?
Not necessarily. If a manhole is buried or concealed, there are location systems that make it possible to determine its position before breaking up the road surface, thereby reducing unnecessary work.
When is it urgent to unblock a drain?
It is advisable to act quickly in the event of sewage backflow, overflows, a risk of flooding, several drains becoming blocked at the same time, or when the water level in the manhole continues to rise.