Suitable for use with clean water that does not contain abrasive particles and liquids that are not chemically aggressive towards the materials from which the pump is made. As a result of their compactness, reliability and the fact that they are easy to use, they are suitable for use in domestic applications such as the distribution of water in combination with small pressure sets, for the irrigation of gardens and allotments, for drawing water from tanks and for all those other situations where air or water may be present in the water to be pumped. The pump comes complete with a flap-check valve. The pump should be installed in an enclosed environment, or at least sheltered from inclement weather.