The message behind the report From Source to Sea is to find and use a better way of managing water to cope with more frequent flooding and drought.
The report calls for a better use of funding and increased co-ordination among land managers.
At the heart of the National Trust report, which was released on 8 October, is improving understanding, and director general Fiona Reynolds said innovation was key. She explained:"It is about thinking about better education and links between agencies; training for people on the ground whose practices make a very real difference."
Rainwater harvesting, as well as using drought-resistant plants and training plants not to require as much watering are some of the good ways of saving water, said Reynolds.
The report highlights the work that the National Trust has been carrying out at Nymans, in Sussex, to conserve water.
"At Nymans, they have reduced watering to just once a month in summer and are still getting an incredible plant display," Reynolds added.