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In the know: How bathroom plumbing works
Room planning

In the know: How bathroom plumbing works

Posted by Rebecca Doody in Room planning | 1 year ago 5 min read

Bathroom plumbing is a complicated thing... but it doesn't need to be. We unpick all your questions on how it works.

When it comes to maintaining your household, there are many things to do and take note of. Knowing a bit more about bathroom plumbing will go a long way in allowing you to better manage all the errands you have to attend to in your household.  Things like managing sewer gas, having access to hot water supply pipes is crucial.

Having the appropriate knowledge of bathroom plumbing will help you when you are looking to remodel or renovate your bathroom and will help in times when you face issues like leakages or clogs. 

In this article, we will be going through the various water systems and pipes and how they all come together. The plumbing system of the place generally consists of the vent pipe, or vent pipes, the drainage system, the sewer gases that occur, the drain waste vent, the sink trap, the hot water heater, and the main water supply line that supplies the bathroom sink and the hot water tank. Sometimes these are also collectively labelled the two plumbing systems in a home's plumbing system, namely the main shut off valve and the septic system.

Identifying your hot water system

Knowing what kind of hot water system your bathroom has is essential in helping you know what bathroom fittings would be suitable for your bathroom. 

There are 3 main categories of hot water systems that your bathroom could possibly have, the low-pressure gravity-fed system, an unvented hot water system, and a system where hot water is created instantaneously. 

The low-pressure gravity-fed system

For one, you most likely have this system as it is the most popular. You can identify that you have this sort of system if you notice that the cold water in your house comes from a storage tank in your loft. Your loft also should have a cylinder for the hot water that can be typically located in a cupboard. Since gravity is controlling the movement of water, pressure is involved in the management of the flow of water.

The unvented hot water system

Then there is the unvented hot water system that has a cylinder that is supplied with cold water via a rising main. This cylinder can handle high levels of pressure and heats up water with the aid of a heating coil. This system works best when the flow rate and pressure of water are kept high.

The combi boiler system 

Finally, another common system that can be found in households is one that uses a combination boiler to instantaneously produce hot water. In this system, cylinders and cisterns usually do not exist. Since the water is supplied from the rising main as well, the water pressure is high in this system.

It is crucial to identify the water system that your bathroom follows so that you can pick appropriate bathroom fixtures that will suit your water system. If your system relies on gravity then you may not get enough pressure from certain fixtures to support your water system. Thus, this is an important aspect to consider when redoing your bathroom.

How to identify your home water system

How do you know your shower type suits your water system?

As mentioned, the water system that your bathroom has will dictate what type of shower you can pick. 

If you have a combination boiler it is best to choose something either a mixer shower or an electric shower. However, you would definitely want to avoid connecting a combination boiler to a pump if you intend to use a mixer shower with a higher rate. Since the water supply comes from the mains, you cannot really use a pump. 

Then, if you have a cylinder that stores hot water, getting a mixer shower that has a pump that increases the rate of water flowing is a viable option. Your other options would also include getting a power shower or an electric shower.

However, one important thing to take note of is that if you do install a pump then you might need to switch out your cylinder for a larger one so that it can match up to the rate of water you want. 

Once the water in your bathroom is drained it goes through large pipes that flow towards the main underground drains. 

In older homes, you probably have a singular pipe for soil and another pipe for wastewater. The pipe for wastewater is usually a smaller pipe while the soil pipe runs on the outside wall and is larger. In homes that have been more recently built, there is usually one main pipe that is designated for all wastes and it is called the soil stack. 

New bathrooms should have a soil pipe but if it is not possible to install one then you can also opt for a small-bore waste pipe paired with a pump. Although it might be more expensive to do this, so you could make sure to take note of this and choose a different location for your bathroom in your household.

Another unique feature of the wastewater system in your bathroom that you might have noticed is how the waste pipes are always in bends. These bends exist such that wastewater can be trapped and sealed so that odours from the wastewater pipes and drains do not diffuse into the bathroom.

How about the pipework for new bathrooms?

The best thing you can do for yourself when redoing your bathroom is to rework the pipework such that your hot and cold water supply pipes also control the flow of wastewater out of your bathroom. Preferably, these pipes should be concealed neatly so that you can have an easy time cleaning your bathroom. 

Another tip to follow is choosing plastic pipeworks as these make your pipes flexible and easily navigate themselves around corners without the need for joints.

If you are also looking to spend less money on redoing your entire bathroom, you can look at making sure that everything is in the same position so that you do not have to redo too much. However, if you do want to rearrange your bathroom, you will need to make sure that your water pipes are appropriately extended and re-routed.


The most important feature of your bathroom that you should be familiar with is the type of water system you have. Once you have this information, any other modifications that you want to make to your bathroom will come easily and will be done well. Other than that, being familiar with your wastewater system will also go a long way.

Author, Rebecca Doody

Posted by Rebecca Doody in Room planning | 1 year ago

Originally from Somerset, Rebecca is our resident copywriter who takes care of all things product related. Rebecca loves the modern interior style with both neutral and bold influences to create a statement look.

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