A land site is a site that provides zero water affinity. Though water sites are tied specifically to the element of water, land sites can have any combination of non-water affinity, or no affinity at all.
For example, a site that provides both fire and air affinity is a land site. A site that provides no affinity is also a land site. A land site is not specifically tied to the element of earth.
If a site provides water affinity and other types of affinity (e.g. earth), it's a water site and not a land site. If a site gains water affinity, then it stops being a land site.
"Land site" and "water site" are mutually exclusive. A site cannot be both a water site and a land site; it will always be one or the other.