How geysers work and what’s inside them

Most of us use geysers daily, for hot showers, washing dishes, or heating water in winter, yet we rarely stop to think about how they work or what’s inside them. Modern geysers might look simple from the outside, but there’s more going on beneath the surface.

Over the years, geysers have evolved from basic mechanical heaters to smarter, more efficient systems with features like Wi-Fi connectivity, induction heating, and advanced insulation. Yet despite these upgrades, they still rely on the same fundamental principles that have powered water heating for decades. In this guide, we’ll explain how geysers work and what’s inside them, so you can better understand the appliance you rely on every day.

How do geysers work?

If you’ve ever wondered what goes on inside your geyser and how it manages to deliver hot water on demand, you’re not alone. Fundamentally, a geyser works on a simple principle: it uses a heating element to warm water and either store it in an insulated tank or deliver it instantly, depending on the type. 

ALSO READ: What is the difference between instant and storage geysers?

There are four main types of water heaters you’ll come across, namely, tank-type water heaters, tankless (or instant) water heaters, hybrid water heaters, and point-of-use water heaters. While their designs and efficiency levels vary, the basic heating mechanism remains similar across models. To understand what’s happening behind the scenes, here’s a closer look at how a typical electric geyser works and what parts are involved:

1. Cold water flows in

When the geyser is switched on, cold water enters through the inlet pipe. In storage geysers, this water collects in a lined metal tank designed to resist rust. Instant geysers skip the storage and heat water on demand. This flow of cold water begins the cycle that heats your water.

2. Heating begins

The geyser’s heating element, usually a metal coil or rod, starts to heat up as it draws power from your home’s electrical supply. In gas geysers, a burner heats the water using LPG or PNG. Many modern geysers use Induction Heat Transfer technology, which heats water faster and more efficiently. Once the heating element is activated, temperature control becomes essential.

3. Temperature control

A thermostat monitors the water temperature inside the tank, automatically shutting off the heating element once the desired temperature is reached. This prevents overheating and energy waste. Many geysers allow you to adjust this setting, giving you control over how hot the water gets.

4. Heat retention

To keep water hot after the heating stops, the tank is insulated with a thick layer of polyurethane foam (PUF). This insulation reduces heat loss, allowing the water to stay warm for hours. Effective heat retention means the geyser doesn’t have to constantly reheat the water, which saves energy.

5. Hot water delivery

Opening the tap sends hot water flowing out through the outlet pipe. As the hot water leaves, fresh cold water enters through the inlet pipe to replace it, ready for the cycle to start again. This continuous flow ensures a steady supply of hot water whenever you need it. But all of this depends on reliable safety systems operating throughout the process.

6. Built-in safety systems

Modern geysers come equipped with safety features designed to protect both the unit and users. A Pressure Release Valve (PRV) prevents dangerous pressure buildup inside the tank.

ALSO READ: 5 causes for a geyser leak and how to solve it

If the unit overheats, a Thermal Cut-off automatically shuts down the heating element to avoid damage or fire risk. Additionally, many electric geysers include an Earth Leakage Circuit Breaker (ELCB), which cuts power instantly if electrical faults are detected, helping prevent shocks or short circuits.

What’s inside a geyser?

Inside a geyser, several important components work together to deliver hot water safely and efficiently. The main component is the inner tank, usually made of rust-resistant stainless steel or lined with glass to keep corrosion at bay. Surrounding the tank is a thick layer of PUF (polyurethane foam) insulation that helps retain heat and improve energy efficiency. 

ALSO READ: An in-depth guide to water heater components

The actual heating happens through an electric coil or, in gas models, a burner that heats the water directly. To control the water temperature, a thermostat monitors and adjusts the heat, ensuring the system does not overheat. The geyser also includes a sacrificial anode, a small metal rod that attracts corrosion to protect the main tank and extend its lifespan.

Water flows in through a cold inlet pipe, gets heated inside the tank, and then exits through the hot water outlet, all packed inside a sturdy metal casing. Together, these parts create the familiar, reliable geyser that keeps your hot showers running smoothly.