I am currently a petroleum geologist and I also enjoy volunteering and public outreach.
When I am asked about drinking water, I draw out the geological formations and explain where the groundwater is produced from and where the hydrocarbons are produced from. One thing to emphasize is scale/depth. I also help the public understand about drilling regulations and our industry's safety standards. Another fun source of information can come from local agencies that have public data about water.
When asked about earthquakes, it is the perfect time to talk about how we measure seismicity and the different types of scales we use. Explaining the logarithmic scale can be a great learning opportunity for adults and kids. This is also a time to talk about background seismicity and plate tectonics. Once an understanding of how we measure seismicity and background seismicity is established, then I refer to any induced seismcity that is published in whatever basin you may be in, and explain the differences between producing hydrocarbons and injecting wastewater.