A desalination system for producing a low salinity injection water for injection in an oil-bearing reservoir containing a connate water, the system comprising: a feed line for a feed water; a first RO stage having a first RO stage inlet fluidly connected with the feed line, a first RO stage permeate outlet for a first RO stage permeate, and a first RO stage concentrate outlet for a first RO stage concentrate; a second RO stage having a second RO stage inlet fluidly connected with the first RO stage concentrate outlet, a second RO stage permeate outlet for a second RO stage permeate, and a second RO stage concentrate outlet for a second RO stage concentrate; an NF stage having an NF stage inlet fluidly connected with the first RO stage concentrate outlet, a NF permeate outlet for an NF permeate, and an NF concentrate outlet for an NF concentrate; and a set of conduits adapted to: (a) connect the feed line to the inlet of the first RO stage; (b) connect the concentrate outlet of the first RO stage to: (i) the inlet of the second RO stage, and (ii) the inlet of the NF stage, such that a first portion of the RO stage concentrate is introduced as second RO stage feed via the second RO stage inlet, and a second portion of the first stage RO concentrate is introduced as NF stage feed via the NF stage inlet; (c) combine: (i) the permeate outlet of the first RO stage, (ii) the permeate outlet of the second RO stage, and (iii) the permeate outlet of the NF stage to form the low salinity injection water; and (d) connect the low salinity injection water either directly or indirectly to a low salinity water injection line, wherein the first RO stage and the second RO stage each comprise a group of RO filtration units arranged in parallel, wherein each of the RO filtration units comprises a pressure vessel containing one or more RO membrane elements, and wherein the NF stage comprises a group of NF filtration units arranged in parallel, wherein each of the NF filtration units comprises a pressure vessel containing one or more NF elements. a feed line for a feed water; a first RO stage having a first RO stage inlet fluidly connected with the feed line, a first RO stage permeate outlet for a first RO stage permeate, and a first RO stage concentrate outlet for a first RO stage concentrate; a second RO stage having a second RO stage inlet fluidly connected with the first RO stage concentrate outlet, a second RO stage permeate outlet for a second RO stage permeate, and a second RO stage concentrate outlet for a second RO stage concentrate; an NF stage having an NF stage inlet fluidly connected with the first RO stage concentrate outlet, a NF permeate outlet for an NF permeate, and an NF concentrate outlet for an NF concentrate; and a set of conduits adapted to: (a) connect the feed line to the inlet of the first RO stage; (b) connect the concentrate outlet of the first RO stage to: (i) the inlet of the second RO stage, and (ii) the inlet of the NF stage, such that a first portion of the RO stage concentrate is introduced as second RO stage feed via the second RO stage inlet, and a second portion of the first stage RO concentrate is introduced as NF stage feed via the NF stage inlet; (c) combine: (i) the permeate outlet of the first RO stage, (ii) the permeate outlet of the second RO stage, and (iii) the permeate outlet of the NF stage to form the low salinity injection water; and (d) connect the low salinity injection water either directly or indirectly to a low salinity water injection line, wherein the first RO stage and the second RO stage each comprise a group of RO filtration units arranged in parallel, wherein each of the RO filtration units comprises a pressure vessel containing one or more RO membrane elements, and wherein the NF stage comprises a group of NF filtration units arranged in parallel, wherein each of the NF filtration units comprises a pressure vessel containing one or more NF elements. (a) connect the feed line to the inlet of the first RO stage; (b) connect the concentrate outlet of the first RO stage to: (i) the inlet of the second RO stage, and (ii) the inlet of the NF stage, such that a first portion of the RO stage concentrate is introduced as second RO stage feed via the second RO stage inlet, and a second portion of the first stage RO concentrate is introduced as NF stage feed via the NF stage inlet; (c) combine: (i) the permeate outlet of the first RO stage, (ii) the permeate outlet of the second RO stage, and (iii) the permeate outlet of the NF stage to form the low salinity injection water; and (d) connect the low salinity injection water either directly or indirectly to a low salinity water injection line,