How much cash emergency fund do I keep?

[Rob Bianco]

I'm shopping around to own 2 million in real estate. It's mostly residential duplex properties with traditional financing. How much of a cash safety net should I have set aside? Properties are relatively low maintenance.

Right now I have roughly $50k set aside which breaks down into $20k for capex, $20k for maintenance, and $10k for vacancy.

I was also planning to set aside 25% of the rental income to add to these categories (capex, maintenance, and vacancy) but am not sure if that is over-the-top and not necessary.

Maybe someone else can let me know what they tend to do?