An emergency fund is a savings buffer set aside to cover unforeseen expenses or financial emergencies like medical bills or car repairs. It provides financial security and helps prevent dipping into long-term investments for urgent needs.

To build an emergency fund using a liquid fund:

1.**Understand Liquid Funds**: These are mutual funds with high liquidity, allowing quick and easy withdrawals.

2.**Assess Your Expenses**: Calculate your monthly living expenses, including bills, groceries, and other essential costs, to determine how much you need in your fund.

3.**Set a Goal**: Aim to save at least 3 to 6 months’ worth of living expenses in your emergency fund.

4.**Regular Contributions**: Decide on a monthly contribution amount and consistently save towards your goal.

5.**Automate Savings**: Set up automatic transfers from your regular account to your liquid fund to ensure consistent savings.

6.**Monitor and Adjust**: Regularly review your fund’s growth and adjust your contributions based on changes in expenses or financial goals.

7.**Choose a Reliable Fund**: Research and choose a liquid fund with a good track record of stability and returns.

8.**Accessing Funds in Emergency**: When needed, redeem units from the liquid fund, providing quick access to cash while maintaining the fund’s stability.

Note: building an emergency fund is about financial preparedness and peace of mind in challenging times.

I can suggest some popular categories of liquid mutual funds in India and some reputed fund houses that historically performed well in this space. It’s important to do your own research and consider consulting a financial advisor for the most up-to-date and suitable options.

1. **SBI Liquid Fund**
2. **ICICI Prudential Liquid Fund**
3. **Aditya Birla Sun Life Liquid Fund**
4. **HDFC Liquid Fund**
5. **UTI Liquid Cash Fund**

These funds are known for their stability, liquidity, and competitive returns in the liquid fund category.

Conclusion: always ensure you thoroughly research and understand the fund’s objectives, past performance, expense ratio, and other relevant factors before making an investment decision.