Where Should a Watermaker Be Installed in the Engine Room?

Where Should a Watermaker Be Installed in the Engine Room?

Space for technical equipment is always limited onboard.

Engines, generators, pumps, batteries, filters and auxiliary systems often share the same technical spaces, which makes the positioning of each component an important part of vessel design.

A watermaker is no exception.

An empty bulkhead or an available corner may initially appear to be a suitable installation point. Yet proper installation involves much more than finding a space where the equipment physically fits.

A good watermaker location provides the right access to water, power and maintenance at the same time.

Installation planning should therefore consider not only how the system will operate today, but also how it will be inspected, maintained and serviced throughout its working life.

Is the Engine Room Always the Best Location?

Watermakers are frequently installed in engine rooms, and for good reason.

The engine room often provides convenient access to seawater plumbing, electrical infrastructure, freshwater tanks and other onboard technical systems. It can also provide strong structural surfaces for secure mounting.

However, being inside the engine room does not automatically make a location suitable.

High ambient temperatures generated by engines and generators, insufficient ventilation or an excessively compact machinery layout can create challenging operating conditions.

This is particularly important when a watermaker is expected to run for extended periods.

The first question should therefore not be:

“Will the watermaker fit here?”

It should be:

“Will the system have the correct operating conditions here?”

1. Ventilation and Ambient Temperature

Temperature is one of the most important considerations in an engine-room installation.

Watermakers contain pumps, electric motors, reverse osmosis membranes and control components, all of which need to operate within the conditions specified by the system manufacturer.

When engines and generators are running, temperatures inside machinery spaces can rise considerably.

A watermaker should therefore:

1. Avoid direct exposure to concentrated engine heat,
2. Be positioned where sufficient airflow is available,
3. Not be enclosed in areas where hot air can accumulate,
4. Be installed within the manufacturer's specified ambient temperature limits.

On some vessels, these requirements may make a modular installation preferable to locating every component in one enclosed area.

2. Plan for Service Access Before Installation

One of the clearest indicators of a well-designed watermaker installation is accessibility.

If replacing a filter requires removing panels, moving other equipment or reaching into an inaccessible section of the engine room, the system may physically fit—but it has not been positioned effectively from an operational perspective.

Components requiring regular inspection or maintenance should remain readily accessible, including:

1. Prefilters,
2. Filter housings,
3. Pumps,
4. Electrical connections,
5. Control components,
6. Pressure and plumbing connections.

The quality of an installation is not determined only by how clean it looks on day one.

It becomes equally apparent during the first filter change.

Required service clearances should therefore be considered before mounting the system, including the direction in which filters, covers and serviceable components need to be removed.

3. Proximity to the Seawater Intake

Seawater is the primary feed source for any marine watermaker.

For that reason, the layout between the seawater intake and the system itself is a critical part of the installation.

Unnecessarily long intake runs, excessive bends or restrictive plumbing can create avoidable losses on the feed side of the system.

As a general engineering principle, pumps should be positioned appropriately in relation to the waterline and intake plumbing should remain as direct, secure and correctly sized as the system specification allows.

The through-hull location itself also matters.

Being close to the watermaker is not enough. The intake should provide a reliable flow of seawater while minimising the risk of drawing air as the vessel moves, heels or encounters rough conditions.

With a watermaker, it is not only about how much water reaches the system, but how reliably it gets there.

4. Keep Prefilters Visible and Accessible

Prefiltration is one of the areas of a watermaker that requires the most frequent inspection.

Installing filters in a dark, inaccessible corner of the engine room may therefore reduce the practicality of the entire system.

A well-planned installation should allow the operator to:

1. Inspect filter condition easily,
2. Reach the filter housing without obstruction,
3. Have sufficient space for replacement,
4. Identify leaks or irregularities quickly.

Easy access is not merely a matter of convenience.

Equipment that can be inspected easily is also more likely to be checked regularly.

For this reason, maintainability should be treated as part of system design rather than an afterthought.

5. Plan Electrical and Plumbing Routes Together

A marine watermaker combines hydraulic, mechanical and electrical systems.

Its electrical infrastructure should therefore not be planned only after the mechanical installation has been completed.

Cable routes should be kept away from:

1. High-temperature surfaces,
2. Moving machinery,
3. Unnecessary exposure to water,
4. Areas where routine servicing may damage them.

Likewise, hoses and plumbing connections should be arranged so that a potential leak does not unnecessarily expose electrical equipment.

A clean technical installation is not simply about appearance.

A system that is easy to read is also easier to inspect, diagnose and service.

6. Consider Vibration and the Mounting Surface

An engine room is naturally a high-vibration environment.

Main engines, generators and auxiliary pumps can transfer mechanical vibration through the vessel's structure. The watermaker's own pumps can also generate movement during operation.

The system should therefore be secured to a structurally suitable surface capable of supporting its operational loads.

Where appropriate, vibration isolation may also be considered.

The objective is not only to reduce noise.

Limiting unnecessary vibration can also help protect connections, hoses and mechanical components over the long term.

7. Plan Product Water and Brine Routes from the Beginning

Watermaker positioning is not only about bringing seawater into the system.

Two separate flows must also leave it:

Fresh product water and concentrated seawater, or brine.

Product water needs a properly planned route to the freshwater tank, while the brine discharge needs to be directed safely overboard in accordance with the system design.

A location that initially appears convenient may therefore become much less practical once all plumbing routes are considered.

A properly integrated installation considers the entire flow path:

Seawater intake → prefiltration → watermaker → freshwater tank / brine discharge

The objective is to keep this system as orderly, efficient and serviceable as possible.

A Compact Installation Is Not Always a Good Installation

Space efficiency is important onboard.

However, fitting technical equipment into the smallest possible area does not automatically represent good engineering.

A well-designed machinery layout balances three requirements:

Space efficiency, operating conditions and serviceability.

Leaving adequate clearance around a watermaker may require slightly more room during installation, but that space becomes valuable during future inspections, filter changes and maintenance.

The Advantage of Modular Installation

Not every vessel has a single ideal space for a complete watermaker assembly.

Modular systems can therefore provide valuable flexibility where machinery-space dimensions are limited.

Depending on system design, pumps, membranes, filters and control components can be distributed across separate but technically suitable locations.

This allows available space to be used according to engineering requirements rather than simply trying to fit an entire system into one compartment.

Component distances, hose runs and mounting conditions must still comply with the technical requirements specified for the particular watermaker.

The Fundamental Principle of Watermaker Placement

There is no universal mounting position that works for every vessel.

The ideal location depends on the vessel, machinery-space layout, waterline, electrical system and the technical requirements of the specific watermaker.

Nevertheless, well-designed installations tend to share the same fundamental characteristics.

The system should be positioned in a cool, ventilated and dry environment, remain accessible for maintenance, connect efficiently to the vessel's plumbing and be mounted securely.

Because installing a watermaker is not simply about finding somewhere onboard to place the equipment.

It is about creating the right technical environment for the system to operate reliably for years to come.