Collect Water From Two Different Water Bodies Around You and Study Them For pH, Clarity and Presence of Any Living Organism


To study pH level, clarity and presence of microbes from two different water bodies.

Necessary Materials & Apparatus

  • Secchi’s Disk
  • Tape
  • Pins
  • Universal Indicator solution
  • Dropper
  • Tile
  • pH paper
  • Beaker
  • Test tube
  • Coverslips
  • Filter paper
  • Glass slides
  • Needles
  • Compound microscope


To study pH levels:

  • Obtain water samples from two different sources of water
  • Dip the individual pH paper strips into the two samples of water.
  • Keep the strips on the tile and wait for them to dry.
  • Alternatively, pH levels of the water sample can also be found using the universal indicator solution.
  • Use the dropper to pour five drops of this solution into a test tube containing the water samples.
  • Note the change in colour and compare the same with the colour chart.

To study the clarity of the water sample:

From a scientific perspective, the number of particles present in a liquid may make it cloudy or hazy. This property is called turbidity. The procedure for finding turbidity of a water body is as follows:

  • Reach the centre of a pond in a boat
  • Immerse Secchi’s disc into the water, lowering it eventually until the black and white segments are no longer visible.
  • Mark the length on the rope where the disk is not visible with a pin. Name this position as “A”
  • Carefully, bring the disc back up and mark the length of rope where disc becomes visible again. Now mark this position as “B”
  • Use a meter tape to measure the length of section A to B
  • Next, find the mean length of the rope by using X= (A+B)/2

To study the presence of living organisms

  • Collect a water sample, preferably from a pond, in a test tube.
  • Leave the sample undisturbed, until the sediment settles at the bottom of the test tube.
  • Transfer a drop from the test tube on to a glass slide.
  • Gently place a coverslip on the slide using a needle.
  • Observe the entire slide using a compound microscope.


To study pH levels:

Note the change in colour and associate the same with a broad range indicator paper to get a rough idea of the pH level.

To study the clarity of the water sample:

The value of X tells us the depth of the photic zone. Below this level, enough light does not penetrate, hence, photosynthesis does not take place.

To study the presence of living organisms:

Pond samples have large numbers of microscopic organisms.


Ensure safety measures are in place when travelling to the centre of the pond.

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