Drawing SWRO feed through the seabed instead of from the open sea — beach wells, infiltration galleries and slant wells that deliver naturally-filtered, low-SDI, low-biofouling seawater with near-zero entrainment of marine life.
A subsurface intake draws seawater through the sand and gravel of the seabed or shoreline rather than from the open water column. That natural slow-sand filtration removes most suspended solids, plankton and organics before the water ever reaches the plant — delivering a low, stable SDI, far less biofouling potential, and effectively zero entrainment of larvae and fish. For the right site, it transforms the economics and the environmental case of a desalination plant by shrinking the pre-treatment train. Reynolds & Bauhm assesses feasibility, yield and water quality, and designs the well or gallery and its pumping.
Wells sunk into a permeable coastal aquifer behind the shoreline — simple and proven for small-to-medium plants where ground conditions and yield allow.
Horizontal screened collector beds buried beneath the seabed or beach, giving large yields with excellent filtration where vertical wells cannot reach demand.
Angled or HDD-drilled wells extending under the seabed combine high yield with a small shoreline footprint — suited to higher-capacity plants.
| Factor | Subsurface intake | Open seawater intake |
|---|---|---|
| Feed SDI / turbidity | Low & stable (pre-filtered) | Variable; full pre-treatment needed |
| Biofouling potential | Low | High — needs chlorination |
| Marine-life entrainment | Near-zero | Managed by velocity & screening |
| Pre-treatment size | Much reduced | Full DAF/media + fine filtration |
| Yield | Site/geology-limited | Effectively unlimited |
| Best for | Suitable geology, smaller plants | Large plants, any coastline |
Permeability, aquifer thickness and recharge set the achievable yield. We assess whether the ground can supply the plant before committing to the approach.
Subsurface feed can carry iron, manganese, hydrogen sulphide or higher CO² that need addressing — we characterise it and design any conditioning required.
Where a single approach falls short, a subsurface intake for base load plus a screened open intake for peaks can deliver the best of both.
Open Intake ScreeningTell us the location, capacity and what is known of the geology — we’ll assess feasibility and design the beach well, gallery or slant-well intake and its pumping.
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