Members of the Royal Institute of Painters in Water Colours are known by the post-nominal letters RI after their names.

Founded in 1831 as the New Society of Painters in Water Colours, it distinguished itself from the older Royal Watercolour Society by exhibiting non-members' work also. Both societies challenged the Royal Academy's refusal to accept the medium of watercolours as appropriate for serious art. It is one of the societies in the Federation of British Artists