A fluid delivery device can be used to deliver fluid within a living body. The fluid delivery device includes an electrochemical pump, a reservoir, a displaceable member, and a diffuse membrane. The electrochemical pump transports water and includes an electrochemical pump product chamber to retain water transported by the electrochemical pump. The reservoir contains a fluid to be delivered. The displaceable member is positioned between the electrochemical pump product chamber and the reservoir. The displaceable member is responsive to the electrochemical pump transporting water into the electrochemical pump product chamber. The diffuse membrane generates increased pressure within the electrochemical pump product chamber.