Too Much Water Too Little Water helps students understand the importance of water. NCERT solution class 4 EVS Chapter 18 is about the quality of the water, whether it is dirty or clean, what dirty water contains, and which technique is used to purify water. This chapter also includes how contaminated water and insufficient sanitization are linked to the transmission of diseases. It has been designed to help students learn about conserving water in the right way, different uses of water as well as the effects of clean and dirty water.