If you find that your coolant in your vehicles is dropping more often than it should then you may have a leaky radiator. Coolant leaks can be a nightmare as often you will be driving along and your water light will suddenly come on. It is not worth the risk driving it with low coolant as it could cause your engine to over heat which can end up being very expensive. Make sure you pull over and top up as soon as possible and if you are aware of a slow leak, make sure you carry water with you.
If you find that it is a leak from a radiator then you may have to fork out a few hundred pounds for a mechanic to buy and fit one for you. I was recently very pleasantly surprised to find a radiator for as little as £53 new. I then found a 30% of voucher code meaning the radiator only cost me £37. I managed to get a friend to fit it so saved myself a small fortune.