2001 Citroen Saxo loosing water

As you probably know , head gasket is a common fault .If it's a leak elsewhere and you think its the block , there are sealants you add to cooling system that you can get from accessory shops or the likes of Halfords . A lot of people swear by them and others only use / try them as a last resort .Your decision , but could try and locate for certain where water is leaking from .A pressure test should show leak better if not sure .