Your Flume app will let you know how your water usage compares to other similar households. But, if you are looking for some guidelines, the EPA estimates that the average American uses around 88 gallons per day per person in the household. That means a family of four would use around 10,500 gallons in a 30-day period.
If you are looking to conserve water, you may want to start by looking at your past water bills. Most water bills will show you how much water you used during the past month. They usually report your usage in terms of Billing Units. A Billing Unit is equal to 748 gallons of water. Once you understand your past water usage, you can set some realistic water usage goals. Then, you can set up "Budgets" in your Flume app to notify you if you are straying from your goals.