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Cistern

technology Maturity 9-11 Next article →

A cistern is a waterproof container used for holding liquids. Most people use them to store fresh water.

Red rain barrel
Red rain barrel

You might think a cistern is like a well. However, they work in very different ways. A well draws water from deep underground. A cistern collects water from other places, like rain.

Well-cistern
Well-cistern

To keep the water from leaking out, people often line the inside with hydraulic plaster. This special plaster stays waterproof so the liquid stays inside.

Many cisterns work by catching rain through a simple process. In places like Bermuda, people use white-stepped roofs to catch rain.

Bermuda roof
Bermuda roof

Gutters then carry that water down into underground cisterns. In the Middle Ages, some people built filter cisterns in European hill castles. One example was at Riegersburg in Austrian Styria. In that system, rainwater passed through a sand filter first. This filter cleaned the water and added minerals to it.

Citernes malga interieur
Citernes malga interieur

People have used cisterns for thousands of years. In the Neolithic period, village sites in the Levant had cisterns in house floors.

Medium sized rock cut cistern at pavuralla konda at bheemunipatnam
Medium sized rock cut cistern at pavuralla konda at bheemunipatnam

In ancient Israel, a large cistern was carved into bedrock at Tel Hazor. This was found beneath a palace from the Late Bronze Age. The Romans also used them in their homes. They used a structure called an impluvium to collect and filter water. This helped to cool and ventilate the house too.

Modern cisterns are used for many important jobs today. In San Francisco, the city has a special firefighting network.

Water cistern in San Francisco
Water cistern in San Francisco

This system, called the AWSS, has 177 underground cisterns. They have a total storage capacity of over 100 million gallons. These help if an earthquake breaks the main water lines. In Brazil, the One Million Cisterns Program helps farmers.

Unterirdische Zisterne
Unterirdische Zisterne

Since 2013, this program has helped people harvest rainwater for drinking and cooking.

You probably interact with a cistern every single day. Most modern toilets use a small cistern to hold water. This water is used to flush the toilet bowl. When you push the lever, the water level drops. This causes a valve to open and let more water in.

Gravity toilet valves handle down
Gravity toilet valves handle down

You can also find cisterns in greenhouses to help plants grow. Some countries even give people tax credits to install them. They are a smart way to save water for the future.

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🖼️ Images & Media (11)
File:El Jadida cistern.jpg
El Jadida cistern.jpg
File:Well-cistern.jpg
Well-cistern.jpg
File:Cistern in the Mission District, San Francisco, California.jpg
Cistern in the Mission District, San...
File:Water cistern in San Francisco.jpg
Water cistern in San Francisco.jpg
File:Medium sized rock cut cistern at pavuralla konda at bheemunipatnam.jpg
Medium sized rock cut cistern at...
File:Citernes malga interieur.jpg
Citernes malga interieur.jpg
File:Unterirdische Zisterne.jpg
Unterirdische Zisterne.jpg
File:Bermuda roof.jpg
Bermuda roof.jpg
File:Gravity toilet valves handle down.svg
Gravity toilet valves handle down.svg
File:Basilica Cistern, Constantinople.jpg
Basilica Cistern, Constantinople.jpg
File:Red rain barrel.jpg
Red rain barrel.jpg
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