Fiber-reinforced composite pipe and cold/warm water piping system

The present invention provides: a fiber-reinforced composite pipe as a multi-layered pipe material having high strength, high dimensional stability, and excellent workability; and a cold/warm water piping system having excellent dimensional stability and improved workability. This fiber-reinforced composite pipe includes: a pipe-shaped first layer including a polyolefin-based resin; a pipe-shaped second layer including a polyolefin-based resin, glass fibers, and a compatibilizing agent; and a pipe-shaped third layer including a polyolefin-based resin; the second layer being disposed on the outer side of the first layer, the third layer being disposed on the outer side of the second layer, the ratio of the thickness of the second layer relative to the total combined thickness of the first layer, second layer, and third layer being 0.3 or more and 0.8 or less, and, within 100 wt% of the second layer, the polyolefin-based resin content being 45 wt% or more and 84 wt% or less, the glass fiber content being 15 wt%