Drainage Meaning (What Is Drainage)

This is the disposal of excess water from a surface. In plants, good drainage is important. This is because it ensures all nutrients are present. However, there are some plants that thrive in swampy areas.

Natural drainage occurs all by itself through the soil. Hence, it is responsible for soil fertility and viability.

Artificial is the one you install by yourself. There are two types of artificial drainage;

  • Surface Drainage

This involves removing soil from the land surface. You will need to construct open drains. Make sure you also put large and deeper collector drains for these to deposit the excess water into. Then create a slope on the land. This will make the water flow into the drains.

  • Subsurface Drainage

This one involves removing water from the soil root zone. It requires buried pipe drains and very deep but open drains.

Excess water flows into the open drains and goes into the buried pipe drains. These then deposit the water in a collector drain.

Drainage System Definition

Every surface needs a drainage system. This is the process by which unwanted water is leached from a surface. Their functionality depends on gravity. The pipes face down to ensure the water moves along. These pipes eventually deposit this wastewater in a sewer or septic tank.

The system includes vents which supply air into your building. This ensures that the wastewater flows out properly. This is why they are usually sticking out of the roof of your house.

Every sink has a trap underneath. Water flows down your sink into the drain pipe through the trap. However, some of the water remains in the trap to prevent sewer gas from coming back in your home.

Every fixture in a building has its own trap. Toilets are self-trapped. Bathtubs have drum traps which also collect hair and dirt. Kitchen sinks have grease traps to collect oils, etc.

Drainage systems are also called DMV (drain-waste-vent-system) because of all the components involved. A drainage system cannot work if all its components are not functioning in sync. A fault at one stage can cause the entire system to shut down. This can be disastrous especially due to all the electrical wiring around buildings.

Types of Drainage Systems

·         Point Drains

It collects water from a specific place and connects to other drainage pipes underground. They are usually in locations that must be drained from a specific point. This could be due to topography or structure. However, they require deep trench support.

·        Trench Drains

These collect water from multiple locations at the same time. Through this, the system gains a higher capacity. There is also reduced chances of pooling water.

They blend in easily with their surrounding and many projects usually incorporate this. It comes in three types;

        Cast-In-Place Trench Drains

In this, manual labourers use wood to create the trench and reinforcing bar to cast the trench. They require grates to cover the trenches which can be made from a variety of materials.

        HDPE Trench Drains

It is made up of pre-engineered modular channel sections that are lightweight and easy to install. However, grates are needed to cover the channel.

They reduce the time and cost of installation. In addition, they offer high chemical resistance in industrial systems.

      Slot Drain Systems

These do not require grates, hence reducing initial cost. They are long and easy to install and are easy to clean due to lack of grates.

Importance of Drainage

  • Reduces Soil Erosion – Drainage maintains balance in your soil moisture. Without drainage, water makes soil muddy hence causing erosion.
  • Eradicates Mosquitoes – Mosquitoes usually breed in stagnant water. When there is drainage, there will be no idle lying water meaning mosquitoes will have no place to breed.
  • Growth of Fungus – Areas, where water has accumulated, do not have enough air flow. Therefore, fungi find favourable conditions to grow.
  • Destabilizing Foundations – Undrained water will run deep into the foundation of your property. This will in turn cause cracks that may collapse the property in time.
  • Termites – They are attracted to moisture. When water accumulates in your foundation, termites are bound to go there. This could cause a huge structural problem.
  • Mould – These are also attracted to moisture and can grow and go unnoticed for a long time. They mostly grow in basements and can be very hazardous for health.
  • Prevents Water Accumulation – Most plants cannot thrive in too much water. Drainage ensures that only the required amount of water is available to the plant.
  •  Getting Rid of Toxins – People living near water sources are prone to flash floods. These may bring harmful toxins. However, with good drainage, they are all flushed away.


This is an underground pipe system that transports sewage from buildings to treatment facilities or to disposal sites. It has manholes that connect the main pipes to the surface. These manholes make it easier to access, inspect and maintain the pipes. It also vents sewer gases.

The pipes that transport sewage from individual buildings are called laterals. The design and size of sewers are determined by the population to be served. Large cities have sewers called interceptors which take sewage flow from multiple trunks. Examples of sewers may include;

·         Vacuum Sewer

This is usually used in low lying communities like homes and businesses. A small grinder pump is usually installed at each point of connection. This is because houses and business have low-pressure systems. They use atmospheric pressure to transport sewage.

·         Effluent Sewer

It is also called septic tank effluent drainage or solid free sewer. They have a septic tank that collects sewage from homes and businesses and takes it to a treatment plant. This plant may be smaller than the typical ones. This is because the septic tank removes all the solid waste. The waste stream in its pipes is pressurized hence pipes can be laid just below the ground.

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