Water Clocks: The Ancient Timekeeper

ancient egypt

Time is precious, and humans have tried to measure it in various ways throughout history. The invention of the clock has revolutionized the way we measure time, and it has come a long way since its inception. One of the earliest and most fascinating timekeepers is the water clock, used by many ancient civilizations. In this article, we will explore how a water clock works and its impact on learning, particularly in ancient Egypt.

What is a water clock?

A water clock, also known as a clepsydra, is an ancient timekeeping device that measures time by the regulated flow of water from a container. The basic principle behind a water clock is that water flows from a container with a small hole at a constant rate and as the water level drops, it indicates the passage of time.

Water clocks were one of the earliest timekeeping devices used by civilizations across the world, dating back to ancient Egypt, Babylon, Greece, and Rome. The size and design of water clocks varied, ranging from small handheld devices to large public clocks. Some water clocks were designed to show the hours of the day, while others measured shorter periods of time.

Why were the invented?

Water clocks were invented as a means of measuring time in ancient societies, where accurate timekeeping was important for various purposes such as regulating religious ceremonies, measuring the length of a workday, and timing public events such as speeches, games, and competitions.

In contrast to sundials, which rely on the movement of the sun across the sky, water clocks could be used to measure time throughout the day and night, regardless of weather or season. Water clocks were also more accurate than sundials, as they could be calibrated to measure shorter intervals of time, such as minutes and seconds.

Moreover, water clocks were portable, reliable, and easy to use, making them widely popular among ancient societies. They could be used by various individuals, from priests and astronomers to merchants and traders, and could be adapted to various settings, including households, temples, and public spaces.

How Water Clocks Work

Water clocks operate on the principle of measuring time by the regulated flow of water from a container. The basic components of a water clock include a container or vessel that holds the water, a regulated outlet or spout, and a measuring scale or marking system to indicate the passage of time.

The water clock works as follows:

  1. A container is filled with liquid water, which flows from the container through a small hole or outlet at a constant rate.
  2. As the water flows out of the container, the water level drops, and the amount of time that has passed is measured by markings on a measuring scale or by observing the position of a floating device within the container.
  3. The rate of flow of water is regulated by the size of the outlet or by a mechanism such as a float or valve, which controls the flow of water.
  4. The water clock can be calibrated to measure different units of time, such as hours, minutes, or seconds, by adjusting the size of the outlet and the size of the container.
  5. The accuracy of the water clock can be improved by using a consistent and precise flow rate, ensuring that the container is level, and maintaining a consistent water temperature.

Overall, water clocks operate by using the regulated flow of water to measure time, making them an important technological advancement in ancient times and a precursor to modern clocks and timekeeping devices.

Sundials or Water Clocks – What are the differences?

Water clocks and sundial clocks are two types of ancient timekeeping devices that operate based on different principles. Here are some of the key differences between the two:

  • Operation: Water clocks use the regulated flow of water to measure time, while sundial clocks use the position of the sun to determine the time of day.
  • Accuracy: Water clocks are generally more accurate than sundial clocks, as they can measure time consistently throughout the day and night, regardless of weather conditions. Sundials rely on the position of the sun and are affected by factors such as cloud cover, shadows, and the changing seasons.
  • Portability: Water clocks are portable and can be moved from one location to another, making them suitable for use in various settings. Sundial clocks, on the other hand, are fixed to a specific location and cannot be easily moved.
  • Measurement: Water clocks can measure time in smaller increments, such as minutes and seconds, while sundial clocks typically measure time in larger increments, such as hours.
  • Complexity: Water clocks are generally more complex than sundial clocks, as they require a mechanism for regulating the flow of water and measuring the passage of time. Sundial clocks, on the other hand, are relatively simple devices that use the position of the sun and shadows to indicate the time of day.

Classic Water Clock Designs

1. Clepsydra: This type of water clock was used by the ancient Greeks and Romans. It had an open container filled with water that would empty into another container with a small hole at the bottom. A scale or markings on the second container would indicate time.

2. Persian Water Clock: Also known as a Qanat, this type of water clock was used by ancient Persian royalty. It had a large water reservoir with a small opening that would empty into a second reservoir with a marked scale to indicate time. The flow rate was carefully controlled with a valve and could be adjusted to compensate for seasonal variations in temperature and humidity.

3. Chinese Water Clock: Known as a jiaozi, this water clock used a dripping mechanism with water trickling from a vessel into a series of small containers with a marked scale. A float would gradually rise in the vessel, triggering the release of the water until the next drip cycle.

4. Arab Water Clock: Also known as a “Elephant Clock,” this elaborate water clock was invented by the Arab inventor Al-Jazari in the 12th century. The clock consisted of a brass elephant with a tower on its back. The tower contained a reservoir of water that would flow into various containers and a series of mechanical animals would move to indicate time.

5. Mayan Water Clock: Known as a Chaacs, this water clock was used by the ancient Maya for timekeeping and religious ceremonies. It consisted of a bowl of water with a hole in the center, surrounded by a ring of carved symbols. A small stick was inserted into the hole and would gradually descend, indicating time by matching the symbols on the ring.

6. Greek Clepsydra: This water clock was similar in design to the Roman version, but also incorporated a float and a pulley system to control the flow of water. The pulley would be used to raise or lower a weight to compensate for the changing water flow.

7. Egyptian Water Clock: The ancient Egyptians used a type of water clock known as a “shadow clock.” It consisted of a flat stone with a raised gnomon, or indicator, that would cast a shadow onto a marked surface. The length of the shadow would indicate time. In conclusion, these water clock designs have been used throughout history to measure time and each have their unique features and qualities.

Understanding Temperature, Water Viscosity, and Clock Accuracy

Over the centuries, water clocks have evolved, and modern designs now incorporate complex mechanisms that combine hydraulics and electronics to keep time accurately. Below we will explore three crucial factors: temperature, water viscosity, and clock accuracy.


The temperature of a water clock’s environment can impact its accuracy. As the temperature changes, water expands or contracts, affecting the amount of water that flows through the clock. This variation can cause inaccuracies in timekeeping.

To counter temperature variations, modern water clocks incorporate temperature compensation mechanisms. These mechanisms ensure that the time indicated remains accurate, regardless of temperature changes.

Water Viscosity

Viscosity is a measure of a fluid’s resistance to flow. The viscosity of water affects the rate at which it flows through the clock. The higher the viscosity, the slower the water flows, and the less accurate the clock.

To ensure accurate timekeeping, water clocks utilize water that has a consistent and precise viscosity. In modern water clocks, the viscosity of the water is often maintained using additives or by using specially formulated water.

Clock Accuracy

The accuracy of a water clock depends on several factors, including the precision of the container dimensions, the size of the water flow hole, and the accuracy of the water’s viscosity. Additionally, external factors, such as air pressure and humidity, can impact the clock’s accuracy.

To ensure precise timekeeping, modern water clocks incorporate advanced microcontrollers that continually monitor and adjust the clock’s operation to remain accurate.

The Modern Water-powered Clock

The need for eco-friendly and sustainable technology has led to the creation of the modern water-powered clock. This game-changing device is powered solely by tap water and operates without any need for electricity or batteries.

The clock’s design is simple: two electrode terminals are placed in a container with water, which becomes an electrolyte. The two electrodes react with each other, causing a flow of ions and creating an electrical current. This current powers the clock.

The advantages of a water-powered clock are numerous. Firstly, it is environmentally friendly, as it produces zero emissions and requires only tap water, which is readily available. Additionally, the average lifespan of a water-powered clock is much longer than a battery-powered clock, as there is no need to replace the battery.

Apart from being eco-friendly, the modern water-powered clock design is also sleek and attractive. Many models feature clear displays, allowing the user to see the mechanism in action. The clock’s minimalist design makes it an ideal addition to any modern living space.

There are various types of water-powered clocks available. Some designs use a proprietary blend of electrolytes, whereas others use pure water to generate the electrical current. Some models also come with additional features, such as an alarm clock or a timer.

The History of The Water Clock

The water clock is one of the most ancient tools used for measuring time. It was widely used throughout the ancient world, including by the Egyptians, Greeks, and Romans. It is believed that the water clock was one of the first devices to be used to measure time and played a significant role in shaping human civilization.

The first known water clock was created by the ancient Egyptians around 1450 BC. It was a bowl filled with water with a small hole in the bottom. As the water flowed out, it trickled down into another container below. The time was read by measuring the height of the water in the lower container.

The Greeks improved on this concept by creating a more advanced water clock that used gears and mechanisms that had to be wound like a modern-day clock. The Greeks also used the water clock to regulate the hours of the day, dividing the day into 12 hours of daylight and 12 hours of darkness.

The Romans also used water clocks, called clepsydras, to regulate the hours of their day. They added features such as bells that rang every hour and even used the water clock to automate their public fountains.

Over time, the water clock evolved, becoming more intricate in design and function. By the 8th century AD, water clocks had become very advanced, with some models featuring intricate mechanisms that could display lunar phases and astronomical events.

The invention of the mechanical clock in the Middle Ages marked the beginning of the end for the water clock. The mechanical clock was more precise and reliable than the water clock and could function 24 hours a day without interruption.

The water clock played a vital role in human history, serving as an essential time-keeping device for thousands of years. Its development marked a significant milestone in the progression of human civilization. Although no longer in use today, its influence can still be seen in modern-day technology.