Water Tank: Basic Components and Classification of Water Tanks

Basic Components and Classification of Water Tanks

A water storage tank is a container for the storage of water for various uses like drinking, sanitation, irrigation, and so on. As water is supplied from the main system only for few hours a day, it comes to be essential to store water to perform different activities throughout the day.

This means that it is important that the water storage tank system is secure, reliable, and suitable for each function. A water tank also requires proper and timely maintenance for the best effective use.

The water storage tanks are classified into three main types,

  1. Water tank based on the location
  2. Water tank based on the materials
  3. Water tanks based on their shape

1. Water tank based on the location

  • (a) Overhead Water Tank
  • (b) Underground Water Tank
  • (c) Water Tank Resting on Ground

(a) Overhead Water Tank


Overhead water storage tanks are used for domestic and commercial water storage purposes. They are generally installed over the rooftop of any house, building, or apartment. Also, the tanks which are constructed over the column or steel structures for the general public water supply or for personal use are included.

These tanks distribute the water through pipelines to the taps. The water tank is filled with the main supply or from an underground water tank.

(b) Underground Water Tank


The water tank which is constructed or placed below the ground level is called an underground tank. Water is filled into these tanks from mains. Water in it is pumped to supply an overhead tank or is pumped directly to the taps. Underground water tanks can be built masonry, RCC, PVC, and many more. 

(c) Water Tank Resting on Ground


This type of water storage tank is built or placed over the ground level. These tanks are in the residential buildings to store water, as a curing tank in the construction sites, in the agricultural area for irrigation purposes, and so on. There can be used several types of materials like masonry, RCC, PVC, fiber, steel for the ground-level water tanks. It will also choose on usage and the cost of the water storage tank.
They are easily accessible and appropriate for daily water usage needs, whether for drinking or home use. These usually need regular inspections and maintenance.

2. Water tank based on the materials

  • (1) R.C.C. Water Tank
  • (2) Masonry Water Tank
  • (3) Plastic Water Tank
  • (4) Fiberglass Water Tank
  • (5) Steel Water Tank

 (1) R.C.C. Water Tank

 These types of water tanks are further classified into two types,

  • (a) Precast Water Tank
  • (b) Cast-in-situ Water Tank

(a) Precast Water Tank


This type of water tank was built in the factory as per size and design and after that shifted to the required place.

(b) Cast-in-situ Water Tank


These types of water storage tanks are very popular for domestic as well as for the general public water supply. These types of water tanks are constructed at the site in the actual place. It can be an overhead water tank or might be underground. Concrete tanks are sturdy and heavy.  Because concrete is porous, they need special care from leaking out.

(2) Masonry Water Tank


These types of water tanks construct by using bricks or blocks in a particular location. It is constructed over the rooftop of any house, building, or apartment or can be built underground and ground level too. They are usually smaller in dimensions when compared to the RCC water tanks, due to their less size it has less water storage capacity.

(3) Plastic Water Tank


Plastic water storage tanks have become very popular now a day. They are strong and light in weight. They are made from polyethylene, a UV stabilized plastic. They are also the cheapest types, easier to place, and very durable. It is corrosion-free and does not rust easily. They are made in one piece and therefore there is no scope for any seam or joints. It comes in a range of colors and can be recycled after its use.

The main problem with plastic tanks is that they can discharge toxic substances as the plastic going down over its lifespan. This is especially harmful if use an old plastic tank for drinking purposes. It can be used as an overhead tank, underground tank as well as tank resting on the ground. 

(4) Fiberglass Water Tank


Fiberglass tanks are truly sturdy and do not rust. It is highly resistant to numerous chemicals, cold temperatures, and corrosion. Therefore it does not break, split and corrode. This is also light in weight and not very costly. They can install as an overhead tank, on ground level or below ground.

 (5) Steel Water Tank


Steel water tanks are composed of galvanized steel, a zinc coating that shields the steel from rust. Steel water storage tanks are strong and are suitable for big storage needs up to thousands of gallons of water.

There are possibilities that a steel storage tank could rust, vastly reducing its lifespan. However, there have been techniques to maintain steel tanks from rusting and make them last for around 15 to 20 years. Steel can be galvanized or coated with polyethylene liners that prevent corrosion.

3. Water tanks based on their shape


The water tanks are molded in a variety of shapes and dimensions.  Some of the common shapes are,

  1. Rectangular water tank.
  2. Circular water tank.
  3. Cylindrical water tank
  4. Oval-shaped water tank.
  5. Spherical tank

Water Storage Tanks Components

Basic Components of Water Storage Tanks are,

  • Inlet Pipes
  • Outlet pipes
  • Drain
  • Overflow
  • Air vents (with insects screen)
  • Level indicator
  • Float valve.

Water Storage Process

Water storage tanks essentially need to have a pipe going in, which is an inlet pipe and a pipe going out, outlet pipe. The inlet pipe is normally connected to the water source, it can be well with a pump or mains water. The outlet pipe is connected to taps and sanitary systems.

To avoid water storage tanks from overflow, a float valve system can be used. A float is attached to a valve, when the water is below a certain level which is called freeboard it fills up the tank, and, when it reaches a required level, it stops the water to come in. There also fixed an overflow pipe that is used when there is a problem and the tank overflows.

A level indicator is fixed to check the level of water inside the water storage tank. As the water level in a tank drops due to usage of water, the empty space is filled by air, when the tank starts to refill the water, the air needs an immediate outlet to move out. The air vent helps to move out the air. There must be a fixed insect screen on the top of the air vents. It prevents any insect to go in.