Heat pumps can be used to extract heat from surface water. This technology is well-suited for use in urban areas. Besides the presence of water, another condition is that the water must have a relatively constant temperature. The offices of Rijkswaterstaat, the Dutch Directorate General for Public Works and Water Management, in Terneuzen, described elsewhere in this publication, have a heat pump that draws heat from the canal water. A seawater system has been realised in the harbour of Scheveningen that extracts heat for approximately 800 new homes from the seawater.