Are portable watermakers any good?

Yes, and often mechanically identical to the installed version of the same model. The trade is convenience, not quality: no through-hulls and no installation bill, but ten minutes of setup and stowing every time you use it.

Is a portable watermaker less efficient than an installed one?

No. Within a range, the portable and modular versions of a model commonly share the same pump and membrane pack, so the watt-hours per litre are identical. Efficiency is set by pump architecture and membrane area, not by whether the unit is bolted down.

Do I need through-hulls for a watermaker?

For an installed system, yes: a seawater intake and a brine discharge. Portable units take their feed over the side and discharge the same way, which is the main reason people choose them.

What is the difference between modular and framed?

Modular splits the pump, filters and membranes into separate components you can distribute around a machinery space. Framed mounts everything on one bracket, which is faster to install and easier to service but needs a single space big enough to take it.

Buying

Portable vs installed watermakers: which suits your boat?

A portable unit avoids the through-hulls and the invoice that comes with them. It also has to be set up, stowed and lived with every time you use it.

5 min read · checked 5 September 2026

This is the first fork in the road for most buyers, and it is less about the watermaker than about how you use the boat. The membranes and pumps are often identical; what changes is where the thing lives and what it takes to start it.

The honest trade

	Portable	Installed (modular or framed)
Purchase price	Similar to the modular equivalent	Similar, plus controls on some models
Installation cost	None	Significant and boat-specific
Through-hulls	None — intake and discharge over the side	Dedicated intake and brine discharge
Setup per use	Fetch, connect hoses, prime, stow after	Open a valve, press a button
Uses the space	Only while running	Permanently
Resale	Goes with you to the next boat	Adds to the boat's value
Realistic use frequency	Lower — friction discourages short runs	Higher — low friction means it gets used

The argument for portable

No holes in the boat, no installer, no waiting for a haul-out. You can buy one this week and use it this weekend. It stows in a locker between trips, which matters on a boat that is not lived aboard. And when you sell the boat, it leaves with you.

It also sidesteps the single biggest variable in the whole purchase. Installation cost is boat-specific and can rival the unit price on a finished interior; a portable unit removes that line from the budget entirely.

The argument for installed

Low friction. A properly installed system is a valve and a switch, which means it gets run most days, which is exactly what membranes want. The intake sits where it will not draw air or dirty harbour water, the brine discharge has a proper route overboard, and nothing has to be lifted or stowed.

Modular systems split the components so the membranes, filters and pump can be distributed around a machinery space — useful on a boat with several small voids rather than one large one. Framed systems keep everything on one bracket, which is quicker to install and much easier to service, if you have the room.

Which one you actually want

Weekend and holiday coastal cruising, boat kept at a marina. Portable. It gets used a handful of times a season and lives in a locker otherwise.
Extended cruising, months at a time, mostly at anchor. Installed. You will run it most days and the friction of a portable becomes a daily annoyance.
Liveaboard. Installed, without much question.
Chartering or a boat that changes hands often. Installed adds to the boat; portable follows you.
You are not sure you want one at all. Portable. It is the reversible decision, and you can sell it easily if you were wrong.

One thing that does not change

Portability has nothing to do with efficiency. Two units from the same range, one portable and one modular, frequently share the same pump and membrane pack, and therefore the same watt-hours per litre. Choose portable or installed on how you use the boat; choose the model on the energy figure.

The same platform, portable and modular

System	Power	Output L/hr	Draw W	Wh per litre	Price
Portable AC 140L Rainman	AC 240V	100–154	1,250	9.8	$5,329
Modular AC 140L Rainman	AC 240V	100–154	1,250	9.8	$5,460
Portable 24VDC 55L Rainman	24V DC	45–61	600	11.3	$4,898
Modular 24VDC 55L Rainman	24V DC	45–61	600	11.3	$5,053

Under 6 Wh/L · energy recovery

6–12 Wh/L

Over 12 Wh/L

Identical output and draw in each pair. The difference is where it lives, not what it costs to run.

Filter by configuration

The comparison table filters by portable, modular or framed, so you can rank within the format you have chosen.

Open the table

Common questions

Are portable watermakers any good?: Yes, and often mechanically identical to the installed version of the same model. The trade is convenience, not quality: no through-hulls and no installation bill, but ten minutes of setup and stowing every time you use it.
Is a portable watermaker less efficient than an installed one?: No. Within a range, the portable and modular versions of a model commonly share the same pump and membrane pack, so the watt-hours per litre are identical. Efficiency is set by pump architecture and membrane area, not by whether the unit is bolted down.
Do I need through-hulls for a watermaker?: For an installed system, yes: a seawater intake and a brine discharge. Portable units take their feed over the side and discharge the same way, which is the main reason people choose them.
What is the difference between modular and framed?: Modular splits the pump, filters and membranes into separate components you can distribute around a machinery space. Framed mounts everything on one bracket, which is faster to install and easier to service but needs a single space big enough to take it.