What are house drainage systems? The Best Answer

A drainage system is a piping network that collects and removes water from wet areas. Drains are mostly used in buildings, roads, and fields. The drainage systems can be underground or open channels in the ground that lead to a body of water or other places of collection. Drains are usually classified as either sanitary drains or stormwater drains.


Sanitary drains carry wastewater to a treatment plant while storm drains serve to carry rainwater off rooftops and into the water table around landforms.

Types of Drains and drainage systems

Drains are classified by their use, into two groups:

In a building, sanitary drains are used to remove wastewater from lavatories and showers while storm drains are used in the roof gutters to drain rainwater. 

Sanitary drains carry wastewater to a treatment plant. Sanitary drainage systems make use of gravity. The liquid wastes are collected and carried away underground level via pipes. Often the water from toilets (black water) is separated from the water that is coming from sinks and showers (grey water). The latter is a lot cleaner and easier to process. Blackwater sometimes has to go in a sewage tank but this depends on the city requirements. Not every house is able to install such a tank as it takes up quite some space.

Storm drains (white water) serve to carry rainwater off rooftops and wet areas and into the water table around landforms. This avoids floods in certain areas of your garden and carries the water to other places. Lower areas in a home or garden can flood quite easily and for this reason, it is important to have a drain that can carry the water away. This is commonly called yard drainage.

 Some houses need to install a rainwater tank and disperse it in the ground. This refills the groundwater and makes sure that it doesn’t lead to floods elsewhere. 

In the past, the same drainage system was used for stormwater and sanitary water. This led to problems during storms as a lot of rainwater was going to the waste treatment facility. They were not able to process all of this water and had to let dirty water flow into rivers.

This made rivers unclean. To avoid this, water companies have started to separate sanitary drains and storm drains. This makes sure that waste treatment facilities can process the dirty water. These are still ongoing works as people only realized quite recently how bad it is to let the water go untreated. 

Where Do Drains Go?

In the simplest sense, drains are pipes that carry away water. The specific type of drain depends on the size of the pipe and its location relative to the source of water. They start from one point (for example a sink) and they come together in a wider drain.

This is sometimes called the main drain. Drains have to be installed at the right angle and vented properly so that the water can mix with air. This lets gravity push the water down towards the sewage treatment facility. A lot of issues can happen when a house doesn’t have a roof vent.

Oxygen is not added to the drains in this instance and the water might be stuck in the drains. This can lead to smells or overflowing sinks. The diameter of the drain also has to be correct for the application.

Plumbers can make mistakes and install drains that are not wide enough. This can lead to problems. This is also the reason why an addition to a home might require a new plumbing system.

People often only install drains that are wide enough for the current applications and don’t anticipate that other devices or sinks will be added. Wider drains cost more and take up more space so often the plumber calculates how wide the drain has to be for the current situation. 

Some countries, such as Brazil don’t allow you to flush toilet paper as the toilet drains are not wide enough. It would result in clogs if you flush toilet paper over there.

Drains are often connected to a complex network of drains that eventually end at a wastewater treatment facility. There the water is cleaned before it gets in rivers and oceans. 

In rural areas, drains are connected with sewage tanks. The processed water gets spread out over the garden with a drainage field. This is a piece of land that is filled with drains so that the water gets spread out over a larger area. The houses are too far away from a processing plant and they have to clean their own wastewater. These tanks need to get pumped from time to time as not all the sewage can get processed. 

Drainage maintenance

The most important thing to do for your drainage system is check on it regularly to make sure there are no clogs or other obstructions that could cause damage to the pipes. You shouldn’t flush wet wipes or other products that can clog up a drain. Unclogging a drain can be quite expensive. Often tree roots grow into drains and destroy them. For this reason, it is important to keep trees away from drains. 

If a pipe bursts, it’s important to fix it as soon as possible because then you’re wasting water and money. Plumbers have cameras that they can use to check what is going on. Water pressure or augers can be used to remove debris from drains. 

Drains should last several decades as they are made with durable plastics such as PVC or PE. In essence, they don’t require a lot of maintenance. Just don’t drive over PVC pipes as they can crack under pressure. They also shouldn’t be exposed to extreme heat as PVC can deform when it gets hot. For this reason, you shouldn’t throw cooking oils in the drain. 

To conclude, we can state that drainage systems are essential in our modern society. They remove dirty water and make sure that parts of our gardens or houses don’t flood. They are generally made out of plastic pipes. These are then interconnected so that gravity can push the water away to another location.

The systems are still evolving as we want to make sure that the wastewater is cleaned as much as possible. This makes sure that we get clean rivers and oceans. These are enormous infrastructures that cost billions of dollars to build and maintain. Some countries don’t have these yet and use simpler systems.  

Drainage systems are complex and take a lot of work to install. A lot of countries don’t have these systems as they are still developing them. They also need a lot of maintenance and other infrastructure, such as wastewater processing plants.

All of this indicates that these are complex systems. In more remote areas, these are not available and a dry toilet can be used instead.