reuse and collection of water for use in agriculture

use all city waste water including blackwater and greywater for use in agriculture 

use greenhouses to avoid water evaporation in agriculture 

collect rainwater harvesting on roofs of all buildings in areas where there is sufficient rainfall and use in agriculture

rainwater harvesting on roofs can easily be combined with solar cells 

collect storm drain water for use in agriculture 

the added cost might be water supply networks connecting agriculture