A Suiton no Jutsu is strong against a fire jutsu, but a sufficiently powerful fire attack can cause a water jutsu to evaporate. Water release will naturally be overcome by a Earth Ninjutsu. Certain water users, such as Hozuki Suigetsu, are also weak against Raiton no Jutsu.
Suiton also has a good relationship with Fuuton; used together, an Water/Wind combo has quite the powerful concussive, offensive, destructive power. The Wind-natured chakra is seen used to add much more pressure to the water technique, giving it more impact force.
Water-natured chakra is a component of at least two, and possibly three, different Kekkei Genkai. When blended with Wind, water can produce Ice. When blended with Earth, water can produce Wood. It is also a component of Storm, together with Lightning.