The building services in most fincas are sometimes not comparable with German standards. It starts with the electricity supply, which does not have the continuity we know from Germany, and ends with the water pressure, the hot water supply, and the lime content and purity of the tap water. Such slight deficits in building services are absolutely normal for the country. However, if there are more serious problems, please contact your landlord or his property management immediately so that any deficiencies can be remedied without delay.
Please remember that tap water is usually not drinking water in Spain.