A tapered flow desalination system comprising: a system inlet feed line coupled to a first high pressure booster pump configured to provide a high pressure feed stream to the system; blocks of membrane pressure vessels (A, B, C) arrayed in parallel, wherein the outlet of said first booster pump is coupled by means of flow lines to said blocks (A, B, C) at first opening sides of said blocks (A, B, C); a second booster pump, coupled at its inlet by a first bypass line parallel to said blocks (A, B, C), to said first booster pump outlet, wherein said second booster pump outlet and inlet are also coupled by means of flow lines to said blocks (A, B, C) at second opening sides of said blocks (A, B, C) and wherein said first bypass line is also coupled by means of flow lines to said blocks (A, B, C) at said second opening sides of said blocks (A, B, C); a system outlet flow line coupled to said first opening sides of said blocks (A, B, C), coupled to said second opening sides of said blocks (A, B, C) and to the second booster pump outlet, wherein said system outlet flow line is coupled to said second opening sides of said blocks (A, B, C) and to said second booster pump outlet by means of a second bypass line; wherein the first bypass line comprises a valve and wherein the second bypass line comprises a valve; wherein at least two of the lines coupling between said first booster pump outlet and said first opening sides of said blocks (A, B, C) each comprise a valve (AFI, BFI, CFI); wherein at least two of the lines coupling between said second booster pump outlet and said second opening sides of said blocks (A, B, C) each comprise a valve (ARI, BRI, CRI); wherein at least two of the lines coupling between said second opening sides of said blocks (A, B, C) and said second booster pump inlet each comprise a valve (AFO, BFO, CFO); and wherein at least two of the lines coupling between said first opening sides of said blocks (A, B, C) and said system outlet flow line each comprise a valve (ARO, BRO, CRO). a system inlet feed line coupled to a first high pressure booster pump configured to provide a high pressure feed stream to the system; blocks of membrane pressure vessels (A, B, C) arrayed in parallel, wherein the outlet of said first booster pump is coupled by means of flow lines to said blocks (A, B, C) at first opening sides of said blocks (A, B, C); a second booster pump, coupled at its inlet by a first bypass line parallel to said blocks (A, B, C), to said first booster pump outlet, wherein said second booster pump outlet and inlet are also coupled by means of flow lines to said blocks (A, B, C) at second opening sides of said blocks (A, B, C) and wherein said first bypass line is also coupled by means of flow lines to said blocks (A, B, C) at said second opening sides of said blocks (A, B, C); a system outlet flow line coupled to said first opening sides of said blocks (A, B, C), coupled to said second opening sides of said blocks (A, B, C) and to the second booster pump outlet, wherein said system outlet flow line is coupled to said second opening sides of said blocks (A, B, C) and to said second booster pump outlet by means of a second bypass line; wherein the first bypass line comprises a valve and wherein the second bypass line comprises a valve; wherein at least two of the lines coupling between said first booster pump outlet and said first opening sides of said blocks (A, B, C) each comprise a valve (AFI, BFI, CFI); wherein at least two of the lines coupling between said second booster pump outlet and said second opening sides of said blocks (A, B, C) each comprise a valve (ARI, BRI, CRI); wherein at least two of the lines coupling between said second opening sides of said blocks (A, B, C) and said second booster pump inlet each comprise a valve (AFO, BFO, CFO); and wherein at least two of the lines coupling between said first opening sides of said blocks (A, B, C) and said system outlet flow line each comprise a valve (ARO, BRO, CRO).