The Bursting Water Pipe


Water is a liquid with a unique property—it expands when it freezes. This expansion can result in a very powerful force when the water is confined. Demonstrate what this incredible force can do to a water pipe in your home!


  • Expansion of water as it freezes
  • Ruptured water pipes
  • Phase diagrams


Ethyl alcohol, 95%, CH3CH2OH, ~ 500–750 mL
Dry ice, CO2, 250–500 g (4 or 5 large pieces)
Ice cubes, 15–20
Water, ~ 800–1200 mL
Beaker, 1- or 2-L, or similar-sized container
Bottle and cap, 500–1000 mL (optional, to save ethyl alcohol)
Coffee can, metal
Demonstration tray, large
Elbow pipe*
Elbow pipe end caps, 2*
Gloves, insulated, or oven mitts (for dry ice)
Gloves, rubber (for ice water bath)
Safety shield and old beach towel
Wrench or pliers
*Materials included in kit.

Safety Precautions

Dry ice is very cold and releases large amounts of carbon dioxide gas when heated. Wear insulated gloves when handling dry ice and use it in a well-ventilated area. Ethyl alcohol is a dangerous fire risk; flammable; addition of denaturant makes it poisonous. Keep away from flames. Wear chemical splash goggles, chemical-resistant gloves and a chemical-resistant apron. Please review current Safety Data Sheets for additional safety, handling and disposal information.

This demonstration should be performed outdoors. Metal fragments may fly in any direction when the pipe breaks. Use a protective safety shield, and cover the can during the demonstration to block the pieces and cold liquid from projecting toward anyone. If the pipe does not burst within 10 minutes after being immersed in the dry ice/ethyl alcohol mixture, do not approach the can immediately. Allow the entire setup to warm up to room temperature before disassembling. Place the metal can containing the dry ice/ethyl alcohol mixture on a large demonstration tray to collect any splattering ethyl alcohol.


Please consult your current Flinn Scientific Catalog/Reference Manual for general guidelines and specific procedures, and review all federal, state and local regulations that may apply, before proceeding. The dry ice/ethyl alcohol mixture should be allowed to warm up to room temperature and degas in a fume hood or outdoors. The ethyl alcohol should be saved for future demonstrations. Excess dry ice should be allowed to sublime in a fume hood or well-ventilated area. The metal pipe pieces may be disposed of according to Flinn Suggested Disposal Method #26a.

Prelab Preparation

(about 30–40 minutes)

  1. Set up an ice water bath: Fill a 1- or 2-L beaker, or similar-sized container, approximately ¾-full with water and ice. If the ice melts quickly, add more ice so that the water will cool for 10 to 15 minutes, with occasional stirring.
  2. As the water cools, use a wrench or pliers to tightly screw one end cap into the elbow pipe. The end cap will most likely not screw all the way down the threads, but get it as tight as possible. A small amount of petroleum jelly can be used as a lubricant if necessary.
  3. Once the water has cooled for 10 to 15 minutes, remove any ice cubes from the ice bath with a spoon.
  4. Completely submerge the elbow pipe, with one screwed-in end cap, into the cold water. Make sure all the air is removed from inside the pipe.
  5. While the elbow pipe is submerged in the cold water, plunge the other end cap into the cold water, turn it over to release any air that may be trapped inside the cap, and then, while the elbow pipe and end cap are under water, screw the end cap into the other end of the elbow pipe. Make sure no air bubbles are inside the cap when it is screwed into the elbow pipe. The excess water inside the pipe and cap will be squeezed through the threads as the cap is screwed in. This end cap only needs to be hand-tightened below the surface of the water. If there is not enough water in the container to allow you to keep both pieces completely submerged when screwing in the end cap, fill the container with additional cold tap water as necessary.
  6. Leave the sealed, water-filled pipe in the water bath and add more ice to fill the container. Allow the water-filled pipe to cool in the ice bath for another 10 to 15 minutes. As the elbow pipe cools, prepare the dry ice/ethyl alcohol bath.
  7. Prepare the dry ice/ethyl alcohol bath in a metal can such as a coffee can. Plastic containers may crack in the cold conditions. Caution: the dry ice/ethyl alcohol mixture should be prepared in an operating fume hood or outdoors. An enormous quantity of carbon dioxide gas will be released as the dry ice sublimes. Wear insulated gloves or oven mitts when handling the dry ice and the cold metal can containing the dry ice/ethyl alcohol bath.
  8. Fill the metal can about half-full with 95% ethyl alcohol. Carefully add 3 or 4 large dry ice pieces to the metal can. A large amount of foggy-white gas (carbon dioxide and ethyl alcohol gas) will billow out of the can as it cools.
  9. Allow the dry ice/ethyl alcohol mixture to cool for 10 to 15 minutes, or until the foggy-white gas flowing from the can appears to slow down and remain steady, and a large amount of frost is seen on the outside of the metal can. Add additional pieces of dry ice if necessary, and make sure the metal container is filled approximately half-full with liquid.


(about 5–15 minutes)

  1. Once the dry ice/ethyl alcohol bath has cooled (10 to 15 minutes), place the can on a large demonstration tray behind a safety shield. Have a thick beach towel or other sheet nearby. Caution: This procedure should be performed outdoors. Wear insulated gloves when handling the cold metal can.
  2. Use tongs to remove the water-filled pipe from the ice water bath. If possible, hand-tighten the end caps further (some water will squeeze through the threads).
  3. Carefully place the water-filled pipe into the dry ice/ethyl alcohol bath behind the safety shield, cover the can with a large towel, and quickly move in front of the safety shield. Stand at least 5 to 10 feet away from the can.
  4. In approximately 2 to 10 minutes, a metallic popping sound will come from the can signifying that the pipe has burst. Some liquid may splash out of the can. Be patient.
  5. Once the pipe has burst, remove the cracked pipe from the dry ice/ethyl alcohol bath with tongs to show your students. Show your students the solid ice that has formed inside the pipe and caused it to burst.
  6. Allow the dry ice/ethyl alcohol bath to warm up to room temperature and degas in a fume hood or outdoors. The ethyl alcohol can be saved and reused for future demonstrations.
  7. When the pipe has warmed up enough, unscrew the end caps, wash them under water, and dry them completely with a towel to prevent rusting. The cracked elbow pipe can be saved to show students in the future or it can be discarded.

Teacher Tips

  • This kit contains enough materials to perform the demonstration twice: two elbow pipes, and two end caps. The end caps will likely not break during the demonstration and can be reused for the other elbow pipe.
  • The preparation of the water-filled pipes will take approximately 30 to 40 minutes. Preparing the dry ice/ethyl alcohol mixture will take approximately 10 to 15 minutes. The freezing/bursting process in the dry ice/ethyl alcohol mixture will take approximately 2 to 10 minutes. Plan time accordingly. The water-filled pipe can be left overnight in a freezer, but it is recommended to place it inside a plastic container with a lid in case it ruptures in the freezer.
  • The ice bath will be cold. If necessary, wear insulated, rubber (Playtex®-type) gloves when screwing the submerged end cap into the elbow pipe to protect hands. Tongs can also be used, but they may be too clumsy.
  • Heating the water before cooling it will release dissolved gases and may help to speed up the bursting time, but the preparation time will be longer. Heat the water to 70–80 °C for a minute or two to release any dissolved gases, allow the water to cool to room temperature, and then add ice cubes.
  • Room-temperature water in the elbow pipe will also work and may save preparation time. However, it will take a much longer time to cool off and freeze the water inside the pipe once it is placed in the dry ice/ethyl alcohol bath. It could take up to 20 minutes and is very unpredictable. For best results, allow the water in the pipe to cool to freezing temperatures for at least 15 minutes before placing it in the dry ice/ethyl alcohol mixture.
  • Patience is very important for this demonstration. As long as the caps are screwed on tightly, and there are no air bubbles inside the pipe, the pipe will eventually burst in the dry ice/ethyl alcohol mixture. It usually takes less than 10 minutes. To prevent anxiety and student’s (and teacher’s) “waiting around in anticipation,” have all the materials ready to go. Explain that the pipe is completely full of water, and place it in the cold dry ice/ethyl alcohol bath. Then, go through an explanation of what happens to water as it freezes. Have student’s guess what might happen to the pipe during the discussion. Has any student experienced broken water pipes in the winter? During the discussion, the pipe should burst, much to the amazement and surprise of the students.
  • The end caps may rust after the demonstration. To prevent this, make sure the caps are unscrewed from the elbow pipe as soon as possible, and that they are washed and dried completely after use. If rust does form on the caps, it can be scraped away with a wire brush. The rust will not affect the integrity of the cap, but it may prevent them from being screwed into or unscrewed from the elbow pipe.
  • The dry ice and the dry ice/ethyl alcohol mixture will be very cold. The freezing point of dry ice at atmospheric pressure is –78.5 °C. The freezing point of ethyl alcohol is –114.1 °C.

Correlation to Next Generation Science Standards (NGSS)

Science & Engineering Practices

Constructing explanations and designing solutions
Developing and using models
Using mathematics and computational thinking

Disciplinary Core Ideas

MS-PS1.A: Structure and Properties of Matter
HS-PS1.A: Structure and Properties of Matter

Crosscutting Concepts

Systems and system models
Stability and change

Performance Expectations

MS-PS1-1. Develop models to describe the atomic composition of simple molecules and extended structures.
MS-PS1-4. Develop a model that predicts and describes changes in particle motion, temperature, and state of a pure substance when thermal energy is added or removed.



The expansion of water as it freezes is a very unusual property. Almost all other materials contract as they get cold, or freeze from liquid to solid. Water expands as it freezes because water molecules form a crystal lattice that takes up more space compared to free-flowing water molecules in liquid water that are not in a rigid pattern. The shape of the water molecules and the strong hydrogen bonds result in a low efficiency, hexagonally packed crystal lattice (see Figure 1).

Since solid water takes up more space than the same mass of liquid water, the density of the solid water must be lower than liquid water. Liquid water at 0 °C has a density of approximately 1.00 g/cm3. (At 4 °C, water is the densest and is defined to have a density of exactly 1.00 g/cm3. At 0 °C, water is slightly less dense than 1.00 g/cm3.) Ice has a density of 0.9168 g/cm3 at 0 °C. This is why ice cubes float on water. The decreased density of water as it transforms into solid ice results in approximately a 9% increase in the volume of ice compared to the initial volume of liquid water. If liquid water is confined as it freezes, a considerable amount of force will be exerted on the containment walls as the water tries to expand and take up more space than is allowed for inside the rigid container.

A rough estimate of the pressure associated with the expansion of water as it freezes in a confined space can be determined using an equation for the isothermal (constant temperature) compressibility of water (Equation 1).


ß = isothermal compressibility constant
Vi = initial volume
Vf = final volume
Pi = initial pressure
Pf = final pressure

The isothermal compressibility of water at 0 °C is equal to 4.7 x 10–5 atm–1. When 100 grams of water is allowed to freeze at 0 °C, the density of the water decreases from 1.00 g/cm3 to 0.9168 g/cm3. This means the volume must increase from 100 mL to 109 mL (1 cm3 = 1 mL). Equation 1 can be used to calculate the amount of pressure that is required to compress 109 mL of water to 100 mL at 0 °C:

Pf – Pi ≈ (1/Vi) x (Vi – Vf)/ß = (1/109 mL) x (109 mL – 100 mL)/4.7 x 10–5 atm–1 = 1760 atm!

If the increased volume due to freezing is prevented, approximately 1760 atm of pressure will be exerted on the walls of a pipe—easily enough to cause the pipe to burst.

{12040_Discussion_Figure_2_Phase diagram of water}

However, the water temperature will need to be lower than 0 °C in order for it to freeze in a confined space such as a water pipe. As the ice crystals attempt to form at 0 °C in a water pipe, the increased volume will result in an increase in pressure on the ice crystals. A pressure increase will actually lower the melting point of water, according to the phase diagram of water (see Figure 2). Therefore, the ice will remelt when the pressure is exerted on it due to its own expansion. According to the phase diagram of water, at pressures less than 2000 atm, the melting point of water changes approximately –0.01 °C for every 1 atm of pressure exerted on it. So, in order for water to freeze with 1760 atm of pressure exerted on it, the temperature must fall to approximately –18 °C (0 °F). This is why water pipes do not usually burst during long periods of “freezing” temperatures. However, in regions where temperatures are well below freezing for long periods of time, it is very important to insulate water pipes to prevent them from rupturing.


Shakhashiri, B. Z. Chemical Demonstrations: A Handbook for Teachers of Chemistry, Vol. 3; University of Wisconsin: Madison, WI, 1989; pp 198–224, 310–312.

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