If the shower is draining slowly, it is usually because the drain or the trap is blocked with hair and soap; if, after clearing them, the water still takes a long time to drain away, the problem lies in the pipework. That is the first question you need to answer, because the solution changes completely.
A slow-draining shower is almost never completely blocked. The water does drain away, but more slowly than it flows in, and it pools in the shower tray whilst you’re showering. Depending on where the blockage is, the causes can be divided into two groups:
- In the drain or siphon: hair, soap, limescale or a slow-flowing drain. This can usually be sorted out at home.
- In the pipework: a gentle slope, limescale build-up, a blocked shared section, or a problem with the downpipe or drain chamber. Domestic cleaning can’t reach those areas.
Below, we explain each cause, how to check in just a few minutes which of the two groups yours falls into, and what to do in each case.
If the shower is draining slowly, it is usually because the drain or the trap is blocked with hair and soap; if, after clearing them, the water still takes a long time to drain away, the problem lies in the pipework. That is the first question you need to answer, because the solution changes completely.
A slow-draining shower is almost never completely blocked. The water does drain away, but more slowly than it flows in, and it pools in the shower tray whilst you’re showering. Depending on where the blockage is, the causes can be divided into two groups:
- In the drain or siphon: hair, soap, limescale or a slow-flowing drain. This can usually be sorted out at home.
- In the pipework: a gentle slope, limescale build-up, a blocked shared section, or a problem with the downpipe or drain chamber. Domestic cleaning can’t reach those areas.
Below, we explain each cause, how to check in just a few minutes which of the two groups yours falls into, and what to do in each case.
Problems with the shower drain and trap
These are the most common and the easiest to sort out. They all have one thing in common: the brake is just a few centimetres from the grille.
Hair and soap residue
It’s the number one cause of problems in any shower. Hair gets caught in the drain grate and the trap, and the soap and shampoo gradually build up around it until it forms a tangled mass that allows less and less water to pass through. It usually starts with the water draining slightly more slowly and ends with water pooling on the shower tray halfway through a shower.
Limescale on the filter and in the siphon
In areas with hard water, limescale builds up on the drain grate, in the trap and in the first few centimetres of pipework, restricting the flow even if there is no hair present. If you live in the Marina Alta, you’ll want to read about how hard water affects your pipework.
Dirty siphon trap
In many bathrooms, particularly in older homes, the shower, washbasin and bidet do not have their own traps: they drain into a shared trap, an accessible container that is usually located on the bathroom floor. When this trap becomes clogged with hair and soap, all the connected fixtures drain more slowly, but the shower is the most affected because it receives the largest volume of water all at once.
A drain with a low flow rate
Not all shower drains carry off the same amount of water. Some extra-flat shower trays have low-profile valves that allow a lower flow rate; if, on top of that, the shower head is delivering a lot of water, the tray will fill up even if the drain is clear. In that case, there is no blockage: the drain simply cannot cope.
When the problem is with the pipework
If you have cleaned the drain grate, the trap or the siphon and the shower is still draining slowly, the blockage is further down the drain. These are the most common causes.
A gentle slope, especially after replacing the bath with a shower tray
Water in the shower flows down by gravity, so the pipework needs a minimum gradient. When a bath is replaced with a shower tray, the drain is lower than before and, if the pipework is not re-laid, it may end up with too little gradient or even a reverse gradient. The water flows slowly and debris always accumulates in the same section. Basic Document HS 5 of the Technical Building Code sets out the requirements for gradients, siphon traps and water seals in drainage systems.
Scale build-up and old pipework
Over the years, limescale and dirt build up to form a hard crust inside the pipe that can no longer be flushed away with water. In older installations, the pipe material itself shrinks in diameter over time, as we explained in our guide on how to prevent recurring blockages in old buildings. If you also notice damp patches or stains, it is worth checking for a burst drainpipe.
A shared section, the downpipe or the manhole
If the shower shares a pipe with other appliances, the blockage may be located beyond the junction. In a flat, it may be in the building’s blocked downpipe; in a house, in a blocked drain pit. If, in addition, water backs up through the shower when you use the toilet or another appliance, it is no longer just a slow drain: it is a backflow, and we explain this in ‘Why does water back up through the drain?’.
Drain or pipe: how to tell at a glance
|
What you notice |
What’s the problem? |
Most likely cause |
|---|---|---|
|
Once you’ve cleaned the drain grate and the trap, it drains properly again |
Drain or siphon |
Hair and soap |
|
Both the shower and the washbasin drain slowly |
Siphon jar |
Dirty siphon trap |
|
It’s been draining slowly ever since the bath was replaced with a shower tray |
Piping |
Slight gradient or reverse gradient |
|
The basin fills up whilst the tap is running, but empties completely when the tap is turned off |
Drain from the dish |
Low-flow valve |
|
It’s running slowly again just a few days after it was cleaned |
Piping |
Inclusions or a deformed section |
|
Several appliances in the house are draining slowly |
Common section, downpipe or manhole |
Blockage in the network |
How to check whether the problem is with the drain or the pipe
In a few minutes, you’ll know which category your shower falls into. Follow these steps in order and stop as soon as the water flow returns to normal.
Step 1: Remove the grille and take out the hair
Remove the drain grate and clear out any hair that has built up using gloves or a plastic hook. Clean the grate as well. If the shower drains properly again, that was the problem.
Step 2: Clean the trap or siphon
If the basin has a removable siphon, remove the cover and clean the inside. If the bathroom has a siphon trap, open the cover on the floor and remove any accumulated dirt. If this improves both the shower and the washbasin, the problem was the siphon trap.
Step 3: Do the bucket test
With the shower turned off, pour a bucket of water into the shower tray in one go. If the water drains away easily when you pour it from the bucket but the tray fills up when you’re having a shower, the drain is clear but the flow is insufficient. If it takes a long time to drain even from the bucket, the blockage is in the pipework.
Step 4: Check what the other drains are doing
Turn on the taps in the washbasin and bidet, and check the drains in other rooms. If only the shower is draining slowly, the problem is in that section of the pipe. If several fixtures are draining slowly, the blockage is in a shared section of pipe, the downpipe or the drain chamber.
What to avoid
Don’t use caustic soda or chemical drain unblockers as a quick fix, and don’t mix different products. We explain why in our guide to common mistakes when trying to unblock pipes yourself. If, as well as the shower draining slowly, it smells bad, find out how to remove bad odours from your pipes.
What to do when the problem is with the pipework
If the bucket test fails, or if the shower starts running slowly again a few days after cleaning it, the blockage is inside the pipe and cannot be reached from the drain. You will need to locate where it is and clear the affected section.
At Limpiezas Domingo e Hijos, we clear blockages and clean pipes using a tanker lorry and high-pressure water. When the problem recurs or it is unclear where the blockage is, we recommend a CCTV inspection of domestic pipes to view the inside of the pipe. If the problem is caused by hard limescale deposits, pipe milling can be used to remove them.
If you’d like to know what the camera might find in a pipe such as the one in your shower, we explain what problems can be detected during a CCTV pipe inspection. And if you’re unsure about another drain in the house, find out when you should call a drain clearance professional.
We operate in La Marina and La Safor. If it’s an emergency, please call 672 450 224.
How to stop the shower from draining slowly again
Almost anything that gets stuck in a shower drains through the drain grate, so prevention starts there:
- Place a hair trap in the drain. It catches the hair before it reaches the trap and empties in seconds.
- Clean the drain grate regularly. Removing hair every few showers prevents a blockage from forming.
- Clean the trap or siphon from time to time. This is where soap and limescale build up.
- Use less product. It is the excess gel, shampoo and conditioner that clogs the drain.
- If you’re replacing the bath with a shower tray, check the pipework. Re-fitting the drain with the correct gradient will prevent the shower from draining slowly right from the start.
For tips that apply to all the drains in your home, see our guide to preventing blocked pipes.
Frequently asked questions about a shower that drains slowly
Why does the shower drain slowly if it isn’t completely blocked?
This is because there is a partial blockage: the water is draining, but more slowly than it is flowing in. The most common cause is hair and soap in the drain or the trap. If the problem persists after cleaning these, the blockage is in the pipe.
Why does water remain in the shower tray?
If water remains in one area of the basin even though the drain is clearing properly, the problem lies with the slope of the basin itself. If water pools around the drain and takes a long time to drain away, the problem lies with the drain or the pipework.
Can an ultra-low-profile shower tray drain more slowly?
Yes. Some extra-flat shower trays have low-profile drains that allow less water to flow through. If the tray fills up whilst the shower is running but drains properly when you turn it off, there is no blockage: the drain simply cannot cope with the flow from the shower head.
What is a siphon trap and why does it affect the shower?
It is a drainable trap, usually located on the bathroom floor, into which the shower, washbasin and bidet drain in many homes. When it becomes clogged with hair and soap, all these fixtures drain more slowly, and the shower is the one where this is most noticeable.
Why is the shower draining slowly since I replaced the bath with a shower tray?
When you replace the bath with a shower tray, the drain is positioned lower down. If the pipework has not been re-laid, there may be insufficient slope or even a reverse slope, meaning that the water drains slowly even if the drain is clear.
First the drain, then the pipe
A shower that drains slowly can almost always be fixed by cleaning the drain grate, the trap or the siphon. If, after doing this, the water still takes a long time to drain away, the problem lies in the pipework, and you’ll need to locate the affected section and clean it thoroughly. If you’re also having problems at home with a toilet that keeps getting blocked or a sink that keeps getting blocked time and time again, there’s a guide for each one.
At Limpiezas Domingo e Hijos, we locate the source of the problem and clean the pipework using a tanker lorry and pressurised water.
Call us on 672 450 224 or 966 447 070, or request a quote.