Why are my leaves turning yellow?
There are two main reasons this may be happening; excess light or over watering. If your ZZ plant is exposed to direct light for too long the leaves will yellow and burn. ZZ plants can adapt to low light, try placing your plant in a darker area of your house. ZZ plants thrive off neglect, so be sure you are not overwatering. Only water your plant once the top 50% of soil is dry.

How tall can a ZZ plant grow?
ZZ plants are fairly slow growing plants that will not grow out of their container very quickly. However overtime they can grow to be up to 3 feet tall!

Why does my ZZ plant have brown leaf tips?
This may be caused by your tap water. Tap water can contain salts, chlorine, minerals and fluoride which can build up in your soil and cause brown leaf tips. Using a water filtration system to filter your water before watering can help with this. You can also try letting your tap water sit in an open container over night to relieve some of the chlorine. Brown leaf tips can also be caused by incredibly dry soil, make sure you are only watering your plant when the top 50-75% of soil is dry.