NCERT Solutions for Class 4th Maths Chapter 8 Water we drink and water we use — Let Us Find
Book page 126 Updated on2026-09-19
Q1.
How many litres of water do you drink in a day? How did you find out?
Answer
Count your glasses, then change them into litres.
Take one glass and see how much it holds. A usual glass holds 250 ml.
Keep a tally mark every time you drink a glass through the day.
Add up at night.
1 glass = 250 ml 4 glasses = 250 + 250 + 250 + 250 = 1000 ml = 1 l 8 glasses = 1 l + 1 l = 2 l
Sample answer: I drank 8 glasses in a day, so I drank about 2 litres of water. I found out by counting my glasses and knowing that 4 glasses make 1 litre.
Why it happens: Counting glasses is easier than measuring straight into litres, and 4 glasses of 250 ml always make exactly 1 litre.
Tip: A Class 4 child should drink about 1½ to 2 litres of water each day, and more on a hot day.
Q2.
How much water can a crow drink at a time?
Answer
A crow is a small bird, so it drinks a very small amount.
A crow’s beak takes in only a few drops at one dip About 10 drops make 1 ml A crow drinks about 5 ml to 10 ml at a time
So a crow drinks about 5 ml to 10 ml at a time — only one or two teaspoonfuls.
Why it happens: A living thing drinks in proportion to its size. A crow is tiny beside us, so it needs only a spoonful where we need a glassful.
Tip: This is why a small bowl of water on your terrace is enough for many birds in summer. Put one out and keep it filled.
Q3.
How much milk do you drink in one day?
Answer
Count your cups or glasses of milk.
1 small glass of milk = about 200 ml Morning 200 ml + night 200 ml = 400 ml
Sample answer: I drink one glass in the morning and one at night. That is 200 ml + 200 ml = 400 ml of milk in a day, a little less than half a litre.
Why it happens: Milk is measured just like water, in millilitres and litres. A packet of milk from the shop is usually 500 ml or 1 l.
Tip: Children should drink about 400 ml to 500 ml of milk a day. Curd and paneer count too.
Q4.
How much water does an elephant drink in a day?
Answer
An elephant is the biggest animal on land, so it drinks a very large amount.
A big bucket holds about 15 l An elephant drinks about 100 l to 150 l in a day That is about 8 to 10 bucketfuls
An elephant drinks about 100 to 150 litres of water in one day.
Why it happens: A body as huge as an elephant’s needs a huge amount of water to keep working. We drink about 2 l a day, and an elephant drinks about fifty times more.
Tip: The Hindi edition asks this question about a cow. A cow drinks about 40 to 50 litres of water in a day.
Q5.
What do you use the most water for? What do you use the least water for? Compare this with a few others in your grade. In which activities is your water usage the same?
Answer
Make a list of everything you use water for, and think how much each one takes.
Activity
About how much water
Most or least?
Washing clothes
About 60 l
Most
Bathing
About 40 l
A lot
Washing utensils
About 20 l
Medium
Watering plants
About 10 l
Medium
Drinking
About 2 l
Least
Brushing teeth
About 1 l
Least
Sample answer: I use the most water for washing clothes and bathing. I use the least water for brushing my teeth. When I asked my friends, the amounts for drinking and brushing teeth were almost the same for all of us. Bathing was different, because some of us use a bucket and some use a shower.
Why it happens: The jobs that clean something big take the most water. Drinking and brushing use very little, so they are nearly the same for everybody.
Tip: Close the tap while brushing. That one small habit saves about 5 litres a day.
Q6.
How much water may be used in the following activities? a. Water for taking a shower b. Watering crops in a field c. Watering flowering plants d. Washing clothes e. ____________ f. ____________
Answer
Some jobs take a bucket, and some take thousands of litres.
Activity
About how much water
a. Water for taking a shower
About 40 l with a shower; only about 20 l with a bucket
b. Watering crops in a field
Thousands of litres — a whole canal or tubewell
c. Watering flowering plants
About 5 l to 10 l — one small bucket
d. Washing clothes
About 60 l for one family wash
e. Washing utensils (your own choice)
About 20 l
f. Mopping the floor (your own choice)
About 10 l
Why it happens: The bigger the thing we are wetting, the more water it needs. A field is far bigger than a flower pot, so it needs far more water.
Tip: Bathing with a bucket instead of a shower saves about 20 litres each time.