Loss of coolant

[Chamberpains]

It can be normal when you have small leaks. There are a lot of places coolant can leak. The suggestions the guys have given you are common but are on the extreme end of coolant leaks. Get yourself a coolant pressure tester and pressurize the system to 20 psi and start fixing leaks. Fix the ones you find and retest for at least an hour. More will likely show up slow and some leaks are stubborn to find. Also take an oil sample and have it tested for coolant intrusion.
Ebay, amazon,walmart or you local Auto parts store should or will have a universal coolant pressure tester kit. The one I got from ebay came with every adapter possible and a vacuum pump for under $100.