7 Water Cycle Experiments for Home or Classroom

The water cycle is taught as a diagram far more often than it is observed. That is a shame, because every stage of it happens somewhere in an ordinary house within a day. Here are seven experiments that make it visible, with honest timings and the questions worth asking.

1. The bag on the window (evaporation and condensation)

You need: a zip bag, a marker, water, tape, a sunny window.
Time: 10 minutes to set up, results within a few hours.

Draw the water cycle onto the bag first — sun, cloud, rain, water. Add a few centimetres of warm water, seal it, tape it to a sunny window. Over the day, droplets form on the inside of the bag and run back down.

Ask: where did the droplets come from? Nothing went in. Nothing came out. So what happened?

2. Cloud in a jar

You need: a jar, hot water, ice, a plate or lid.
Time: 5 minutes.

Pour hot water into the jar, swirl and tip most of it out, cover with a plate and put ice on top. A visible cloud forms where warm rising vapour meets the cold surface.

Common mistake: not enough temperature difference. If nothing happens, the water was not hot enough or the ice was not cold enough.

Ask: a cloud needs two things here. What are they?

3. Rain in a jar

You need: a clear glass, water, shaving foam, blue food colouring.
Time: 10 minutes.

Fill the glass with water, float a layer of foam on top as the cloud, then drip coloured water onto the foam. It holds for a while — and then breaks through in streaks.

Ask: why did the “rain” not fall straight away? This is the best available demonstration of a cloud reaching saturation.

4. Evaporation race

You need: three identical saucers, water, a measuring spoon.
Time: 5 minutes a day for three days.

Same amount of water in each. One on a sunny sill, one in the shade, one in the fridge. Mark the level each day.

Why it matters: this is the first proper fair test in the list — one variable changed, everything else kept the same. Insist on recording numbers rather than “less”.

5. Transpiration bag

You need: a clear bag, a rubber band, a leafy plant outdoors.
Time: set up in 2 minutes, check after a few hours.

Seal the bag around a leafy branch. Water collects inside. Plants are part of the cycle too — a fact usually skipped in the diagram.

6. Salt water to fresh (a mini distillation)

You need: a large bowl, a small cup, salty water, cling film, a small weight.
Time: set up in 10 minutes, results over several hours in the sun.

Put salty water in the bowl, stand the empty cup in the middle, cover with cling film, place the weight above the cup so the film dips. Water evaporates, condenses on the film, runs down and drips into the cup — leaving the salt behind.

Important: do not drink it. This is a demonstration of a process, not a way to make drinking water.

Ask: if the salt did not evaporate, where is it now?

7. Groundwater in a bottle

You need: a clear bottle cut in half, gravel, sand, soil, water.
Time: 15 minutes.

Layer gravel, then sand, then soil. Pour water on slowly and watch it soak down and collect at the bottom. That pooled water is the water table — the part of the cycle that is invisible in most diagrams because it is underground.

How to make them count

An experiment that ends in “cool” teaches very little. Three habits change that:

• Predict before you start. Write it down, wrong answers included.
• Record what happened, not what should have happened. This is the hardest one, and the most valuable.
• Change one thing and repeat. Two runs beat one every time.

Take it further

• My Water Cycle Activity Workbook — recording pages for these investigations
• The Amazing Water Cycle — a short self-paced course for ages 8–12
• Water Cycle in a Bag Classroom Kit — the class-set version of experiment 1

---

Written by the Watershed Learning curriculum team. We write and test every resource we sell. Factual content is checked against current, reputable sources before publication and reviewed when we update the article. Spotted something wrong? Tell us — we would rather know.
Last updated: 19 August 2026.