The Israelites made two unwise choices:
They left the Lord, their true source of life
Thet started worshipping false gods that could not help them
A fountain of living (running) water that flows all year, even during droughts, is a rare treasure (Psalm 36:9; John 4:14).
The cisterns the Israelites built after entering Canaan were holes in the ground lined with plaster. These simple tanks collected rainwater from roofs during wet weather and provided water during dry summers. The water could become stale and unsafe to drink, and the plaster often cracked, causing the water to leak out.