How karez irrigation system is done?

In the villages of India (especially Punjab) and Pakistan, a small reservoir of water is made at the outlet of the tube well. This reservoir is used for bathing and recreational purposes, especially by children. In most South Asian countries including India, Pakistan, Bangladesh, etc., taking a bath in the tube well is popular as it allows people to avoid paying for their own electricity and water for a bath. Bathing in tube well reservoirs can lead to illness.