Lowland wetland sites with a permanent supply of unpolluted neutral to alkaline water. There are 3 known naturally-occurring populations in the UK: in East Anglia, East Sussex and South Wales. New populations have now been established at further sites in East Anglia, as part of a conservation programme to reduce their vulnerability. Locally, the best site to spot the fen raft spider is at SWT Redgrave and Lopham Fen. The species it may be confused with, the raft spider (Dolomedes fimbratus), is found on acidic mires and wet lowland heaths.