The main source of drinking water for Bantwal and Mangaluru (Mangalore) in Karnataka is the river:

The Netravati (Netravathi) river is the main source of drinking water for Mangaluru (Mangalore) city and the town of Bantwal in the Dakshina Kannada district of Karnataka.

Course of the Netravati:

• It rises at Bangrabalige in the Kudremukh area of the Western Ghats, in the Chikkamagaluru district of Karnataka.
• It flows west through the Dakshina Kannada district, past the pilgrimage town of Dharmasthala and the town of Bantwal.
• Near Uppinangady, it is joined by its main tributary, the Kumaradhara.
• It joins the Gurupura (Phalguni) river near Mangaluru and enters the Arabian Sea.
• Its length is about 103 km.

Water supply:

• A vented dam at Thumbe, near Mangaluru, stores water for the city's drinking water supply.
• The water is supplied through pipelines to Mangaluru and other towns.

Yettinahole project:

The Yettinahole Integrated Drinking Water Project aims to divert water from the Yettinahole, a tributary of the Netravati, to the dry districts of Kolar, Chikkaballapur and parts of Bengaluru. It has been opposed by people in Dakshina Kannada, who fear reduced flow in the Netravati.

Dharmasthala:

Dharmasthala, on the banks of the Netravati, is famous for the Manjunatha temple, a centre of Shiva worship managed by a Jain family, and for its tradition of free meals and charity.

Features of west-flowing rivers of Karnataka:

• They are short and swift, rising in the Western Ghats and flowing to the Arabian Sea.
• They receive heavy rainfall during the south-west monsoon and often flood.
• Other such rivers include the Sharavati, Kali (Kalinadi), Aghanashini, Gangavalli and Varahi.

Why not the other options?

• ✗The Sharavati flows into the sea at Honnavar in Uttara Kannada.
• ✗The Kali flows into the sea near Karwar.
• ✗The Tungabhadra is an east-flowing tributary of the Krishna.