Western Region and similar camps often read 10,000–15,000 mg/L and can swing higher. A BW 8040 element is not built for that osmotic pressure or that salt rejection. We specify SW 8040 (Filmtec / Toray / Hydranautics class). Starting point on a 100,000 GPD camp machine: 20 elements in 4 × 5-element 600 psi FRP vessels. Flux is held conservative so nameplate still holds when TDS climbs toward 15,000–20,000 mg/L.
Pretreatment is stricter than BW: tighter cartridges, antiscalant selected for seawater scaling ions (CaSO₄, CaCO₃, silica watch), acid if LSI requires it, zero free chlorine on the membrane (SMBS if the well is shocked). HP pump duty rises with osmotic pressure. Product TDS is managed by rejection and, if required, a small second pass — not by “pushing” a BW array.
100,000 GPD containerized SW RO on ~12,300 mg/L feed. BOQ: 20 × SW8040, specified HP and feed pumps, 4 vessels 5-el 600 psi, 2 × FRP 4272, CIP, Italian dosing, SS304 + PVC lots, contactor panel with dry-run and plant protection. Lump-sum plus VAT; advance staged per LPO (75% or 25/50/25).
Ajban-class plants that still carry BW 8040 on 11,700+ mg/L feed lose production (35–38k GPD on a 75k nameplate). Recommendation is seawater high-rejection 8040 replacement of the full set, plus a working TDS meter. Upgrade path: add one 5-element 600 psi vessel and five SW elements to push toward 100,000 GPD if the pumps and pipe allow.
Included: array, vessels, pumps, pretreatment as BOQ, container if ordered, commissioning. Excluded unless ordered: open-sea intake screens, beach wells, energy-recovery PX (that sits on UHPRO / large SW), remineralisation for a potable network, civil tanks.
Latest analysis (TDS can move — design on the high month, not the best day), required GPD, power, and whether product is potable-spec or utility-spec.
